Uncovering Egyptian Blue Pigment With Photo-Induced Luminescence

!!!!

CRANFIELD UNIVERSITY

C Armstrong

UNCOVERING EGYTPTIAN BLUE PIGMENT WITH PHOTO-INDUCED LUMINESCENCE

CRANFIELD DEFENCE AND SECURITY [Forensic Archaeology and Anthropology]

MSc THESIS Academic Year: 2012-2013

Supervisors: A Shortland and K Domoney July 2013

CRANFIELD UNIVERSITY

CRANFIELD DEFENCE AND SECURITY

DEPARTMENT OF FORENSIC ARCHAEOLOGY AND ANTHROPOLOGY

Forensic Modular Masters THESIS

Academic Year 2012-2013

C ARMSTRONG

Uncovering Egyptian Blue Pigment with Photo-Induced Luminescence

Supervisors: Drs Andrew Shortland and Kelly Domoney

July 2013

This thesis is submitted in partial fulfilment of the requirements for the degree of Master of Science.

© Cranfield University 2012. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright owner.

!

C.H. Armstrong FMM-13 1!

ABSTRACT

Photo-induced luminescence is used in this study to excite Egyptian blue pigment so that a

digital image can be recorded showing the exact location of the pigment within a piece of art.

Control tests were run to find the optimal settings for the modified camera to be able to detect

the pigment; this was followed by comparison tests between dark and light conditions,

indirect and direct sunlight, and other minerals. Finally, the modified camera was used at the

Ashmolean Museum to test twenty-five objects from different places and periods for the

presence of Egyptian blue pigment.

Egyptian blue pigment was used over a 4000-year period in many cultures around the world

and remained chemically consistent throughout this period. The way in which it was used has

great historical value as conclusions can be drawn about the cultures that used it,

contemporary manufacturing processes, and the trade routes of the ancient world which

enabled the pigment to be so widely used without a significant change in its chemical

makeup. Thus, the ability to detect the pigment where it is no longer visible to the human eye

is of great interest to the archaeological and historical communities.

The results of the artefacts at the museum varied, but importantly, this study proved that

contrary to previous studies, dark room conditions need not be observed to obtain good

results using this technique. Some limitations of the technique were observed, such as the

detection limitations of the modified camera to properly detect the pigment which include

extreme weathering, and possibly the use of binding medium, or conservation techniques,

though future study could further illuminate this issue.

!


ACKNOWLEDGEMENTS !Thank you to Marie Svobada, Giacomo Chiari, and BJ Farrar at the Getty Institute for their help with the experimental design of this study. Thank you to the Ashmolean Museum for the use of their artefacts and facilities, and to Mark Norman and Jevon Thistlewood for their help with the experiments. Thank you to Andrew Shortland and Kelly Domoney for supervising this study at Cranfield University, and to Adrian Mustey and the workshop at the Stephenson Laboratory at Cranfield University for making the adapter for the flash filter for the modified camera.

!


LIST OF CONTENTS ABSTRACT .........................................................................................................................................1!

ACKNOWLEDGEMENTS .................................................................................................................2!

LIST!OF!CONTENTS .........................................................................................................................3!

LIST!OF!FIGURES..............................................................................................................................5!

Chapter!1:!INTRODUCTION.......................................................................................................21!1.1!Egyptian!Blue....................................................................................................................................21!1.1.1!What!is!Egyptian!blue? ............................................................................................................................21!1.1.2!Why!it!emits!luminescence....................................................................................................................22!1.1.3!How!it!was!made........................................................................................................................................23!1.1.4!How!it!was!used..........................................................................................................................................25!1.1.5!When!it!came!in!and!out!of!use............................................................................................................26!

1.2!Previous!work!on!this!technique...............................................................................................29!1.2.1!What!equipment!was!used!and!how!it!was!used .........................................................................29!1.2.2!What!results!were!obtained..................................................................................................................31!1.2.3!Suggested!further!work...........................................................................................................................32!1.2.4!Problems!distinguishing!between!Egyptian!blue,!Han!blue,!and!Han!purple .................32!

1.3!Materials ............................................................................................................................................33!1.3.1!What!equipment!was!used ....................................................................................................................33!1.3.2!Why!the!equipment!was!chosen..........................................................................................................33!

1.4!Aims!and!objectives........................................................................................................................34!

Chapter!2:!METHODOLOGY.......................................................................................................35!2.1!Camera!set!up...................................................................................................................................35!2.2!Control!set!up ...................................................................................................................................36!2.2.1!Conditions!of!control ................................................................................................................................36!2.2.2!How!results!are!read ................................................................................................................................38!

2.3!Dark!vs.!light!test!set!up................................................................................................................38!2.3.1!Conditions!of!experiment!in!dark .......................................................................................................38!2.3.2!Conditions!of!experiment!in!light .......................................................................................................39!2.3.3!Conditions!of!experiment!in!indirect!sunlight ..............................................................................39!2.3.4!Conditions!of!experiment!in!direct!sunlight ..................................................................................39!

2.4!Other!minerals!test!set!up............................................................................................................39!2.4.1!List!of!minerals!that!were!tested ........................................................................................................39!2.4.2!Conditions!of!tests .....................................................................................................................................42!

2.5!Ashmolean!Museum!materials!test!set!up..............................................................................42!2.5.1!List!of!materials!that!were!tested .......................................................................................................42!2.5.2!Conditions!of!tests .....................................................................................................................................45!

Chapter!3:!RESULTS.....................................................................................................................47!3.1!Light!vs.!dark!test!results .............................................................................................................47!3.1.1!Dark!results ..................................................................................................................................................47!3.1.2!Light!results..................................................................................................................................................51!3.1.3!Indirect!sunlight!results..........................................................................................................................54!3.1.4!Direct!sunlight!results..............................................................................................................................58!

3.3!Other!minerals!results ..................................................................................................................61!3.3!Ashmolean!Museum!materials!results ....................................................................................88!

!


3.3.1!Egyptian!objects:!Old!Kingdom............................................................................................................88!3.3.4!Egyptian!objects:!Middle!Kingdom ....................................................................................................89!3.3.3!Egyptian!objects:!New!Kingdom .........................................................................................................91!3.3.4!Shrine!of!Taharqa ......................................................................................................................................94!3.3.5!Near!East!objects........................................................................................................................................99!3.3.6!GraecoVRoman!objects.......................................................................................................................... 100!3.3.7!RomanoVEgyptian!Objects................................................................................................................... 103!

Chapter!4:!DISCUSSION ........................................................................................................... 107!4.1!Dark!vs!light!discussion ............................................................................................................. 107!4.2!Other!minerals!discussion ........................................................................................................ 108!4.3!Old!Kingdom!objects!from!the!Ashmolean!Museum!discussion .................................. 108!4.4!Middle!Kingdom!objects!from!the!Ashmolean!Museum!discussion ........................... 108!4.5!New!Kingdom!objects!from!the!Ashmolean!Museum!discussion ................................ 110!4.6!Near!East!objects!from!the!Ashmolean!Museum!discussion ......................................... 114!4.7!Graeco[Roman!objects!from!the!Ashmolean!Museum!discussion............................... 115!4.8!Romano[Egyptian!objects!from!the!Ashmolean!Museum!discussion......................... 116!4.9!General!discussion!and!suggested!further!study .............................................................. 118!

Chapter!5:!CONCLUSION.......................................................................................................... 120!

BIBLIOGRAPHY.......................................................................................................................... 121!!!!

!


LIST OF FIGURES Figure 1: Schematic representation of the experimental setup used for visible-induced

luminescence imaging of Egyptian blue (Verri, 2009a: 3). .............................................30!Figure 2: a) visible RCB image of the blue pigments; b) red-induced luminescence image in

the 800-1000 range; c) red-induced luminescence in the 800-1700 range (Verri, 2009a: 6). .....................................................................................................................................31!

Figure 3: Schematic representation of the way in which the system of camera and filters works................................................................................................................................34!

Figure 4: Front view of flash and camera. ...............................................................................35!Figure 5: Side view of flash and camera..................................................................................36!Figure 6: Back view of flash and camera. ...............................................................................36!Figure 7: Laboratory set up overview......................................................................................37!Figure 8: Sample and infrared detection card set up. ..............................................................37!Figure 9: Side view of the Ashmolean frame with the camera mounted on it. .......................45!Figure 10: Front view of the Ashmolean frame with the camera mounted on it. ....................46!Figure 11: Egyptian blue sample: dark; macro focusing range; flash exposure: 0..................47!Figure 12: Egyptian blue sample: dark; normal focusing range; flash exposure: +1/3. ..........47!Figure 13: Egyptian blue sample: dark; macro focusing range; flash exposure: +2/3. ...........47!Figure 14: Egyptian blue sample: dark; normal focusing range; flash exposure: +1. .............47!Figure 15: Egyptian blue sample: dark; normal focusing range; flash exposure: +1 1/3. .......48!Figure 16: Egyptian blue sample: dark; macro focusing range; flash exposure: +1 2/3. ........48!Figure 17: Egyptian blue sample: dark; macro focusing range; flash exposure: +2................48!Figure 18: Egyptian blue sample: dark; macro focusing range; flash exposure: +2 1/3. ........48!Figure 19: Egyptian blue sample: dark; macro focusing range; flash exposure: +2 2/3. ........48!Figure 20: Egyptian blue sample: dark; macro focusing range; flash exposure: +3................48!Figure 21: Egyptian blue sample: dark; normal focusing range; flash exposure: 0. ...............49!Figure 22: Egyptian blue sample: dark; normal focusing range; flash exposure: +1/3. ..........49!Figure 23: Egyptian blue sample: dark; normal focusing range; flash exposure: +2/3. ..........49!Figure 24: Egyptian blue sample: dark; normal focusing range; flash exposure: +1. .............49!Figure 25: Egyptian blue sample: dark; normal focusing range; flash exposure: +1 1/3. .......49!Figure 26: Egyptian blue sample: dark; normal focusing range; flash exposure: +1 2/3. .......49!Figure 27: Egyptian blue sample: dark; normal focusing range; flash exposure: +2. ............50!Figure 28: Egyptian blue sample: dark; normal focusing range; flash exposure: + 2 1/3. ......50!Figure 29: Egyptian blue sample: dark; normal focusing range; flash exposure: +2 2/3. .......50!Figure 30: Egyptian blue sample: dark; macro focusing range; flash exposure: +3................50!Figure 31: Egyptian blue sample: dark; manual focus focusing range (18); flash exposure +2

1/3. ...................................................................................................................................50!Figure 32: Egyptian blue sample: light; macro focusing range; flash exposure: 0..................51!Figure 33: Egyptian blue sample: light; macro focusing range; flash exposure: +1/3. ...........51!Figure 34: Egyptian blue sample: light; macro focusing range; flash exposure: +2/3. ...........51!Figure 35: Egyptian blue sample: light; macro focusing range; flash exposure: +1. ..............51!Figure 36: Egyptian blue sample: light; macro focusing range; flash exposure: +1 1/3. ........51!Figure 37: Egyptian blue sample: light; macro focusing range; flash exposure: +1 2/3. ........51!Figure 38: Egyptian blue sample: light; macro focusing range; flash exposure: +2. ..............52!Figure 39: Egyptian blue sample: light; macro focusing range; flash exposure: +2 1/3. ........52!Figure 40: Egyptian blue sample: light; macro focusing range; flash exposure: +2 2/3. ........52!Figure 41: Egyptian blue sample: light; macro focusing range; flash exposure: +3. ..............52!

!


Figure 42: Egyptian blue sample: light; normal focusing range; flash exposure: 0. ...............52!Figure 43: Egyptian blue sample: light; normal focusing range; flash exposure: +1/3. ..........52!Figure 44: Egyptian blue sample: light; normal focusing range; flash exposure: +2/3. ..........53!Figure 45: Egyptian blue sample: light; normal focusing range; flash exposure: +1. .............53!Figure 46: Egyptian blue sample: light; normal focusing range; flash exposure: +1 1/3. .......53!Figure 47: Egyptian blue sample: light; normal focusing range; flash exposure: +1 2/3. .......53!Figure 48: Egyptian blue sample: light; normal focusing range; flash exposure: +2. .............53!Figure 49: Egyptian blue sample: light; normal focusing range; flash exposure: +2 1/3. .......53!Figure 50: Egyptian blue sample: light; normal focusing range; flash exposure: +2 2/3. .......54!Figure 51: Egyptian blue sample: light; normal focusing range; flash exposure: +3. .............54!Figure 52: Egyptian blue sample: light, manual focus focusing range (18); flash exposure: +2

1/3. ...................................................................................................................................54!Figure 53: Egyptian blue sample: indirect sunlight; manual focus focusing range (18); flash

exposure: -3......................................................................................................................54!Figure 54: Egyptian blue sample: indirect sunlight; manual focus focusing range (18); flash

exposure: -2 2/3. ..............................................................................................................54!Figure 55: Egyptian blue sample: indirect sunlight; manual focus focusing range (18); flash






exposure: -2/3. .................................................................................................................55!Figure 61: Egyptian blue sample: indirect sunlight; manual focus focusing range (18); flash

exposure: -1/3. .................................................................................................................56!Figure 62: Egyptian blue sample: indirect sunlight; manual focus focusing range (18); flash

exposure: 0. ......................................................................................................................56!Figure 63: Egyptian blue sample: indirect sunlight; manual focus focusing range (18); flash

exposure: +1/3..................................................................................................................56!Figure 64: Egyptian blue sample: indirect sunlight; manual focus focusing range (18); flash

exposure: +2/3..................................................................................................................56!Figure 65: Egyptian blue sample: indirect sunlight; manual focus focusing range (18); flash

exposure: +1.....................................................................................................................56!Figure 66: Egyptian blue sample: indirect sunlight; manual focus focusing range (18); flash

exposure: +1 1/3...............................................................................................................56!Figure 67: Egyptian blue sample: indirect sunlight; manual focus focusing range (18); flash


exposure: +2.....................................................................................................................57!Figure 69: Egyptian blue sample: indirect sunlight; manual focus focusing range (18); flash



exposure: +3.....................................................................................................................57!

!


Figure 72: Egyptian blue sample: direct sunlight; manual focus focusing range (18); flash exposure: -3......................................................................................................................58!

Figure 73: Egyptian blue sample: direct sunlight; manual focus focusing range (18); flash exposure: -2 2/3. ..............................................................................................................58!






Figure 79: Egyptian blue sample: direct sunlight; manual focus focusing range (18); flash exposure: -2/3. .................................................................................................................59!

Figure 80: Egyptian blue sample: direct sunlight; manual focus focusing range (18); flash exposure: -1/3. .................................................................................................................59!

Figure 81: Egyptian blue sample: direct sunlight; manual focus focusing range (18); flash exposure: 0. ......................................................................................................................59!

Figure 82: Egyptian blue sample: direct sunlight; manual focus focusing range (18); flash exposure: +1/3..................................................................................................................59!

Figure 83: Egyptian blue sample: direct sunlight; manual focus focusing range (18); flash exposure: +2/3..................................................................................................................59!

Figure 84: Egyptian blue sample: direct sunlight; manual focus focusing range (18); flash exposure: +1.....................................................................................................................60!

Figure 85: Egyptian blue sample: direct sunlight; manual focus focusing range (18); flash exposure: +1 1/3...............................................................................................................60!






Figure 91: Phyllite: Loch Leven, West Scotland: normal; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................61!

Figure 92: Phyllite: Loch Leven, West Scotland: light; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................61!

Figure 93: Phyllite: Loch Leven, West Scotland: dark; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................61!

Figure 94: Rhyolite: Scotland: normal; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................................................................................61!

Figure 95: Rhyolite: Scotland: light; manual focus focusing range (20); flash exposure: +2 1/3 ....................................................................................................................................61!

Figure 96: Rhyolite: Scotland: dark; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................................................................................61!

!


Figure 97: Granodiorite: beside the loch at Strontian, Scotland: normal; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................62!

Figure 98: Granodiorite: beside the loch at Strontian, Scotland: light; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................62!

Figure 99: Granodiorite: beside the loch at Strontian, Scotland: dark; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................62!

Figure 100: Andesite: Gatesgarth, Buttermere, Cumbria: normal; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................62!

Figure 101: Andesite: Gatesgarth, Buttermere, Cumbria: light; manual focus focusing range (20); flash exposure: +2 1/3 .............................................................................................62!

Figure 102: Andesite: Gatesgarth, Buttermere, Cumbria: dark; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................62!

Figure 103: Diorite-Quartz: lower Glen Coe, Scotland: normal; manual focus focusing range (20); flash exposure: +2 1/3 .............................................................................................62!

Figure 104: Diorite-Quartz: lower Glen Coe, Scotland: light; manual focus focusing range (20); flash exposure: +2 1/3 .............................................................................................62!

Figure 105: Diorite-Quartz: lower Glen Coe, Scotland: dark; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................62!

Figure 106: Diorite: Cockermouth, Cumbria: normal; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................63!

Figure 107: Diorite: Cockermouth, Cumbria: light; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................63!

Figure 108: Diorite: Cockermouth, Cumbria: dark; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................63!

Figure 109: Quartzite and malachite and cuproadant: Cap Garonne, Var, France: normal; manual focus focusing range (20); flash exposure: +2 1/3. .............................................63!

Figure 110: Quartzite and malachite and cuproadant: Cap Garonne, Var, France: light; manual focus focusing range (20); flash exposure: +2 1/3. .............................................63!

Figure 111: Quartzite and malachite and cuproadant: Cap Garonne, Var, France: dark; manual focus focusing range (20); flash exposure: +2 1/3. .............................................63!

Figure 112: Quartzite: Holy Island, Anglesey: normal; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................63!

Figure 113: Quartzite: Holy Island, Anglesey: light; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................63!

Figure 114: Quartzite: Holy Island, Anglesey: dark; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................63!

Figure 115: Pegmatite (pink feldspar/quartz): Evje area, South Norway: normal; manual focus focusing range (20); flash exposure: +2 1/3...........................................................64!

Figure 116: Pegmatite (pink feldspar/quartz): Evje area, South Norway: light; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................64!

Figure 117: Pegmatite (pink feldspar/quartz): Evje area, South Norway: dark; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................64!

Figure 118: Alnoite: Alno island, Baltic coast, Sweden: normal; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................64!

Figure 119: Alnoite: Alno island, Baltic coast, Sweden: light; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................64!

Figure 120: Alnoite: Alno island, Baltic coast, Sweden: dark; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................64!

Figure 121: Porphyry: Alvadalen, Mora, Sweden: normal; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................64!

!


Figure 122: Porphyry: Alvadalen, Mora, Sweden: light; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................64!

Figure 123: Porphyry: Alvadalen, Mora, Sweden: dark; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................64!

Figure 124: Porphyry (Quartz-Porphyry): Armboth Dyke Thirlwere, Cumbria: normal; manual focus focusing range (20); flash exposure: +2 1/3. .............................................65!

Figure 125: Porphyry (Quartz-Porphyry): Armboth Dyke Thirlwere, Cumbria: light; manual focus focusing range (20); flash exposure: +2 1/3...........................................................65!

Figure 126: Porphyry (Quartz-Porphyry): Armboth Dyke Thirlwere, Cumbria: dark; manual focus focusing range (20); flash exposure: +2 1/3...........................................................65!

Figure 127: Porphyry (Quartz-Porphyry): Gwennap, Cornwall: normal; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................65!

Figure 128: Porphyry (Quartz-Porphyry): Gwennap, Cornwall: light; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................65!

Figure 129: Porphyry (Quartz-Porphyry): Gwennap, Cornwall: dark; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................65!

Figure 130: Slate with Chiastolite: Glenderaterra near Skiddaw, Cumbria: normal; manual focus focusing range (20); flash exposure: +2 1/3...........................................................65!

Figure 131: Slate with Chiastolite: Glenderaterra near Skiddaw, Cumbria: light; manual focus focusing range (20); flash exposure: +2 1/3...........................................................65!

Figure 132: Slate with Chiastolite: Glenderaterra near Skiddaw, Cumbria: dark; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................65!

Figure 133: Aplite: near Scirignac, Brittany, France: normal; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................66!

Figure 134: Aplite: near Scirignac, Brittany, France: light; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................66!

Figure 135: Aplite: near Scirignac, Brittany, France: dark; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................66!

Figure 136: Pegmatite (Zircon in Quartz and Feldspar): Ontario, Canada: normal; manual focus focusing range (20); flash exposure: +2 1/3...........................................................66!

Figure 137: Pegmatite (Zircon in Quartz and Feldspar): Ontario, Canada: light; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................66!

Figure 138: Pegmatite (Zircon in Quartz and Feldspar): Ontario, Canada: dark; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................66!

Figure 139: Porphyry, France: normal; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................................................................................66!

Figure 140: Porphyry, France: light; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................................................................................66!

Figure 141: Porphyry, France: dark; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................................................................................66!

Figure 142: Porphyry, Canisp, Scotland: normal; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................67!

Figure 143: Porphyry, Canisp, Scotland: light; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................67!

Figure 144: Porphyry, Canisp, Scotland: dark; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................67!

Figure 145: Pitchstone: Arran, Scotland: normal; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................67!

Figure 146: Pitchstone: Arran, Scotland: light; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................67!

!


Figure 147: Pitchstone: Arran, Scotland: dark; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................67!

Figure 148: Gneiss Stronian, Argyllshire, Scotland: normal; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................67!

Figure 149: Gneiss Stronian, Argyllshire, Scotland: light; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................67!

Figure 150: Gneiss Stronian, Argyllshire, Scotland: dark; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................67!

Figure 151: Mudstone: Kimmeridge, Dorset, England: normal; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................68!

Figure 152: Mudstone: Kimmeridge, Dorset, England: light; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................68!

Figure 153: Mudstone: Kimmeridge, Dorset, England: dark; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................68!

Figure 154: Shale: Kimmeridge, Dorset, England: normal; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................68!

Figure 155: Shale: Kimmeridge, Dorset, England: light; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................68!

Figure 156: Shale: Kimmeridge, Dorset, England: dark; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................68!

Figure 157: Agglomerate: Glen Coe, Scotland: normal; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................68!

Figure 158: Agglomerate: Glen Coe, Scotland: light; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................68!

Figure 159: Agglomerate: Glen Coe, Scotland: dark; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................68!

Figure 160: Obsidian: USA: normal; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................................................................................69!

Figure 161: Obsidian: USA: light; manual focus focusing range (20); flash exposure: +2 1/3..........................................................................................................................................69!

Figure 162: Obsidian: USA: dark; manual focus focusing range (20); flash exposure: +2 1/3..........................................................................................................................................69!

Figure 163: Gneiss (black and white): Scotland: normal; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................69!

Figure 164: Gneiss (black and white): Scotland: light; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................69!

Figure 165: Gneiss (black and white): Scotland: dark; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................69!

Figure 166: Slate: Delabole Quarry, near Tintagel, North Cornwall: normal; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................69!

Figure 167: Slate: Delabole Quarry, near Tintagel, North Cornwall: light; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................69!

Figure 168: Slate: Delabole Quarry, near Tintagel, North Cornwall: dark; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................69!

Figure 169: Siltstone: Moughton Whetstone, near Austwick, Yorkshire: normal; manual focus focusing range (20); flash exposure: +2 1/3...........................................................70!

Figure 170: Siltstone: Moughton Whetstone, near Austwick, Yorkshire: light; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................70!

Figure 171: Siltstone: Moughton Whetstone, near Austwick, Yorkshire: dark; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................70!

!


Figure 172: Breccia: Brockram, Cumbria: normal; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................70!

Figure 173: Breccia: Brockram, Cumbria: light; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................70!

Figure 174: Breccia: Brockram, Cumbria: dark; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................70!

Figure 175: Granite Strontian: Argylshire, Scotland: normal; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................70!

Figure 176: Granite Strontian: Argylshire, Scotland: light; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................70!

Figure 177: Granite Strontian: Argylshire, Scotland: dark; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................70!

Figure 178: Granite Shap: Cumbria: normal; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................71!

Figure 179: Granite Shap: Cumbria: light; manual focus focusing range (20); flash exposure: +2 1/3. ..............................................................................................................................71!

Figure 180: Granite Shap: Cumbria: dark; manual focus focusing range (20); flash exposure: +2 1/3. ..............................................................................................................................71!

Figure 181: Granite (Pink Granite): normal; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................71!

Figure 182: Granite (Pink Granite): light; manual focus focusing range (20); flash exposure: +2 1/3. ..............................................................................................................................71!

Figure 183: Granite (Pink Granite): dark; manual focus focusing range (20); flash exposure: +2 1/3. ..............................................................................................................................71!

Figure 184: Granite Merrivale: Dartmoor, Devon: normal; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................71!

Figure 185: Granite Merrivale: Dartmoor, Devon: light; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................71!

Figure 186: Granite Merrivale: Dartmoor, Devon: dark; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................71!

Figure 187: Granite: Rapakivi, Finland: normal; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................72!

Figure 188: Granite: Rapakivi, Finland: light; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................72!

Figure 189: Granite: Rapakivi, Finland: dark; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................72!

Figure 190: Granite: Redhills, Skye, Scotland: normal; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................72!

Figure 191: Granite: Redhills, Skye, Scotland: light; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................72!

Figure 192: Granite: Redhills, Skye, Scotland: dark; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................72!

Figure 193: Granite: Le’Etacq Quarry, Jersey, Channel Islands: normal; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................72!

Figure 194: Granite: Le’Etacq Quarry, Jersey, Channel Islands: light; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................72!

Figure 195: Granite: Le’Etacq Quarry, Jersey, Channel Islands: dark; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................72!

Figure 196: Granite Pophyry with pink feldspars: Camborne, Cornwall: normal; manual focus focusing range (20); flash exposure: +2 1/3...........................................................73!

!


Figure 197: Granite Pophyry with pink feldspars: Camborne, Cornwall: light; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................73!

Figure 198: Granite Pophyry with pink feldspars: Camborne, Cornwall: dark; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................73!

Figure 199: Granite: Eepoo, Finland: normal; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................73!

Figure 200: Granite: Eepoo, Finland: light; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................73!

Figure 201: Granite: Eepoo, Finland: dark; manual focus focusing range (20); flash exposure: +2 1/3. ..............................................................................................................................73!

Figure 202: Granite Pegmatite: Durness, Sutherland, Scotland: normal; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................73!

Figure 203: Granite Pegmatite: Durness, Sutherland, Scotland: light; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................73!

Figure 204: Granite Pegmatite: Durness, Sutherland, Scotland: dark; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................73!

Figure 205: Phyllite: Belmont Unst, Shetlands: normal; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................74!

Figure 206: Phyllite: Belmont Unst, Shetlands: light; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................74!

Figure 207: Phyllite: Belmont Unst, Shetlands: dark; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................74!

Figure 208: Basalt: Skye, Scotland: normal; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................74!

Figure 209: Basalt: Skye, Scotland: light; manual focus focusing range (20); flash exposure: +2 1/3. ..............................................................................................................................74!

Figure 210: Basalt: Skye, Scotland: dark; manual focus focusing range (20); flash exposure: +2 1/3. ..............................................................................................................................74!

Figure 211: Basalt: near Sanquahar, Ayrshire, Scotland: normal; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................74!

Figure 212: Basalt: near Sanquahar, Ayrshire, Scotland: light; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................74!

Figure 213: Basalt: near Sanquahar, Ayrshire, Scotland: dark; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................74!

Figure 214: Basalt: Sconser, Skye, Scotland: normal; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................75!

Figure 215: Basalt: Sconser, Skye, Scotland: light; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................75!

Figure 216: Basalt: Sconser, Skye, Scotland: dark; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................75!

Figure 217: Gabbro: Dalgellau, Wales: normal; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................75!

Figure 218: Gabbro: Dalgellau, Wales: light; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................75!

Figure 219: Gabbro: Dalgellau, Wales: dark; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................75!

Figure 220: Quartzite: Ightham, near Sevenoaks, Kent: normal; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................75!

Figure 221: Quartzite: Ightham, near Sevenoaks, Kent: light; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................75!

!


Figure 222: Quartzite: Ightham, near Sevenoaks, Kent: dark; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................75!

Figure 223: Agglomerate: Cwrm Llan, Snowdoria, Wales: normal; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................76!

Figure 224: Agglomerate: Cwrm Llan, Snowdoria, Wales: light; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................76!

Figure 225: Agglomerate: Cwrm Llan, Snowdoria, Wales: dark; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................76!

Figure 226: Dolerite: Derbyshire: normal; manual focus focusing range (20); flash exposure: +2 1/3. ..............................................................................................................................76!

Figure 227: Dolerite: Derbyshire: light; manual focus focusing range (20); flash exposure: +2 1/3. ..............................................................................................................................76!

Figure 228: Dolerite: Derbyshire: dark; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................................................................................76!

Figure 229: Gabbro: Caldbeck Fells, Cumbria: normal; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................76!

Figure 230: Gabbro: Caldbeck Fells, Cumbria: light; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................76!

Figure 231: Gabbro: Caldbeck Fells, Cumbria: dark; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................76!

Figure 232: Gabbro: Porthoustock, Lizard, Cornwall: normal; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................77!

Figure 233: Gabbro: Porthoustock, Lizard, Cornwall: light; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................77!

Figure 234: Gabbro: Porthoustock, Lizard, Cornwall: dark; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................77!

Figure 235: Sandstone: Achnahaird Bay, North/West Scotland: normal; manual focus focusing range (20); flash exposure: +2 1/3 . ..................................................................77!

Figure 236: Sandstone: Achnahaird Bay, North/West Scotland : light; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................77!

Figure 237: Sandstone: Achnahaird Bay, North/West Scotland: dark; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................77!

Figure 238: Sandstone: near St David’s, Pembrokeshire, Wales: normal; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................77!

Figure 239: Sandstone: near St David’s, Pembrokeshire, Wales: light; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................77!

Figure 240: Sandstone: near St David’s, Pembrokeshire, Wales: dark; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................77!

Figure 241: Sandstone: Surrey: normal; manual focus focusing range (20); flash exposure: +2 1/3. ..............................................................................................................................78!

Figure 242: Sandstone: Surrey: light; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................................................................................78!

Figure 243: Sandstone: Surrey: dark; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................................................................................78!

Figure 244: Sandstone: Femgirous, Hurtanter, Norfolk: normal; manual focus focusing range (20); flash exposure: +2 1/3 .............................................................................................78!

Figure 245: Sandstone: Femgirous, Hurtanter, Norfolk: light; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................78!

Figure 246: Sandstone: Femgirous, Hurtanter, Norfolk: dark; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................78!

!


Figure 247: Sandstone: Miscaeus, Yorkshire: normal; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................78!

Figure 248: Sandstone: Miscaeus, Yorkshire: light; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................78!

Figure 249: Sandstone: Miscaeus, Yorkshire: dark; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................78!

Figure 250: Sandstone: near Penrite, Cumbria: normal; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................79!

Figure 251: Sandstone: near Penrite, Cumbria: light; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................79!

Figure 252: Sandstone: near Penrite, Cumbria: dark; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................79!

Figure 253: Sandstone: Godalmina, Surrey: normal; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................79!

Figure 254: Sandstone: Godalmina, Surrey: light; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................79!

Figure 255: Sandstone: Godalmina, Surrey: dark; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................79!

Figure 256: Sandstone with Glauconite: Cow Gap, Eastbourne, Sussex: normal; manual focus focusing range (20); flash exposure: +2 1/3...........................................................79!

Figure 257: Sandstone with Glauconite: Cow Gap, Eastbourne, Sussex: light; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................79!

Figure 258: Sandstone with Glauconite: Cow Gap, Eastbourne, Sussex: dark; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................79!

Figure 259: Sandstone, Cumbria: normal; manual focus focusing range (20); flash exposure: +2 1/3. ..............................................................................................................................80!

Figure 260: Sandstone, Cumbria: light; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................................................................................80!

Figure 261: Sandstone, Cumbria: dark; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................................................................................80!

Figure 262: Limestone (Shelly limestone): normal; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................80!

Figure 263: Limestone (Shelly limestone): light; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................80!

Figure 264: Limestone (Shelly limestone): dark; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................80!

Figure 265: Limestone: Headon beds, near Freshwater, I.O.W.: normal; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................80!

Figure 266: Limestone: Headon beds, near Freshwater, I.O.W.: light; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................80!

Figure 267: Limestone: Headon beds, near Freshwater, I.O.W.: dark; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................80!

Figure 268: Limestone, Derbyshire: normal; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................81!

Figure 269: Limestone, Derbyshire: light; manual focus focusing range (20); flash exposure: +2 1/3. ..............................................................................................................................81!

Figure 270: Limestone, Derbyshire: dark; manual focus focusing range (20); flash exposure: +2 1/3 ...............................................................................................................................81!

Figure 271: Limestone (Crinoidal limestone): Derbyshire: normal; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................81!

!


Figure 272: Limestone (Crinoidal limestone): Derbyshire: light; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................81!

Figure 273: Limestone (Crinoidal limestone): Derbyshire: dark; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................81!

Figure 274: Chaulk: near Effingham, Surrey: normal; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................81!

Figure 275: Chaulk: near Effingham, Surrey: light; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................81!

Figure 276: Chaulk: near Effingham, Surrey: dark; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................81!

Figure 277: Marble: Skye, Scotland: normal; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................82!

Figure 278: Marble: Skye, Scotland: light; manual focus focusing range (20); flash exposure: +2 1/3. ..............................................................................................................................82!

Figure 279: Marble: Skye, Scotland: dark; manual focus focusing range (20); flash exposure: +2 1/3. ..............................................................................................................................82!

Figure 280: Marble: Carrara, Apuan area, Italy: normal; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................82!

Figure 281: Marble: Carrara, Apuan area, Italy: light; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................82!

Figure 282: Marble: Carrara, Apuan area, Italy: dark; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................82!

Figure 283: Eclogite, Nordfjord, Norway: normal; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................82!

Figure 284: Eclogite, Nordfjord, Norway: light; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................82!

Figure 285: Eclogite, Nordfjord, Norway: dark; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................82!

Figure 286: Hornfels: near Carrock Mine, from Skiddaw area, Cumbria: normal; manual focus focusing range (20); flash exposure: +2 1/3...........................................................83!

Figure 287: Hornfels: near Carrock Mine, from Skiddaw area, Cumbria: light; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................83!

Figure 288: Hornfels: near Carrock Mine, from Skiddaw area, Cumbria; normal; manual focus focusing range (20); flash exposure: +2 1/3...........................................................83!

Figure 289: Schist: Scotland: normal; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................................................................................83!

Figure 290: Schist: Scotland: light; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................................................................................83!

Figure 291: Schist: Scotland: dark; manual focus focusing range (20); flash exposure: +2 1/3..........................................................................................................................................83!

Figure 292: Schist: Arnes, near Oslo, Norway: normal; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................83!

Figure 293: Schist: Arnes, near Oslo, Norway: light; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................83!

Figure 294: Schist: Arnes, near Oslo, Norway: dark; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................83!

Figure 295: Schist (Garnet Schist): Glen Roy, West Scotland: normal; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................84!

Figure 296: Schist (Garnet Schist): Glen Roy, West Scotland: light; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................84!

!


Figure 297: Schist (Garnet Schist): Glen Roy, West Scotland: dark; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................84!

Figure 298: Fine-grain Biotite Schist and Garnets: Sweden: normal; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................84!

Figure 299: Fine-grain Biotite Schist and Garnets: Sweden: light; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................84!

Figure 300: Fine-grain Biotite Schist and Garnets: Sweden: dark; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................84!

Figure 301: Schist and Horblende: Kopparberg, Sweden: normal; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................84!

Figure 302: Schist and Horblende: Kopparberg, Sweden: light; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................84!

Figure 303: Schist and Horblende: Kopparberg, Sweden: dark; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................84!

Figure 304: Tuff: near Church Stretton, Shroshire: normal; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................85!

Figure 305: Tuff: near Church Stretton, Shroshire: light; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................85!

Figure 306: Tuff: near Church Stretton, Shroshire: dark; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................85!

Figure 307: Tuff: Sheddesdale, Cumbria: normal; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................85!

Figure 308: Tuff: Sheddesdale, Cumbria: light; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................85!

Figure 309: Tuff: Sheddesdale, Cumbria: dark; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................85!

Figure 310: Tuff (“Green Slate”): Borrowdale, Cumbria: normal; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................85!

Figure 311: Tuff (“Green Slate”): Borrowdale, Cumbria: light; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................85!

Figure 312: Tuff (“Green Slate”): Borrowdale, Cumbria: dark; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................85!

Figure 313: Ignimbrite: Dingle Peninsula, South Ireland: normal; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................86!

Figure 314: Ignimbrite: Dingle Peninsula, South Ireland: light; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................86!

Figure 315: Ignimbrite: Dingle Peninsula, South Ireland: dark; manual focus focusing range (20); flash exposure: +2 1/3. ............................................................................................86!

Figure 316: Pumice: Italy: normal; manual focus focusing range (20); flash exposure: +2 1/3..........................................................................................................................................86!

Figure 317: Pumice: Italy: light; manual focus focusing range (20); flash exposure: +2 1/3.86!Figure 318: Pumice: Italy: dark; manual focus focusing range (20); flash exposure: +2 1/3..86! Figure 319: Tephrite with Leucite, Taualota, Rome: normal; manual focus focusing range

(20); flash exposure: +2 1/3. ............................................................................................86! Figure 320: Tephrite with Leucite, Taualota, Rome: light; manual focus focusing range (20);

flash exposure: +2 1/3......................................................................................................86!Figure 321: Tephrite with Leucite, Taualota, Rome: dark; manual focus focusing range (20);

flash exposure: +2 1/3......................................................................................................86! Figure 322: Tuff (“Birds Eye”): Long Sleddodale, Cumbria: normal; manual focus focusing

range (20); flash exposure: +2 1/3. ..................................................................................87!

!


Figure 323: Tuff (“Birds Eye”): Long Sleddodale, Cumbria: light; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................87!

Figure 324: Tuff (“Birds Eye”): Long Sleddodale, Cumbria: dark; manual focus focusing range (20); flash exposure: +2 1/3. ..................................................................................87!

Figure 325: Trachyte: Puy de la Tache, Mont Dere, Puy de Dome, France: normal; manual focus focusing range (20); flash exposure: +2 1/3...........................................................87!

Figure 326: Trachyte: Puy de la Tache, Mont Dere, Puy de Dome, France: light; manual focus focusing range (20); flash exposure: +2 1/3...........................................................87!

Figure 327: Trachyte: Puy de la Tache, Mont Dere, Puy de Dome, France: dark; manual focus focusing range (20); flash exposure: +2 1/3...........................................................87!

Figure 328: AN1885.504: normal; manual focus focusing range (30); flash exposure +2 1/3..........................................................................................................................................88!

Figure 329: AN1885.504: with filters; manual focus focusing range (30); flash exposure +2 1/3. ...................................................................................................................................88!

Figure 330: AN1885.504 (top right corner): normal; manual focus focusing range (22); flash exposure: +2 1/3...............................................................................................................88!

Figure 331: AN1885.504 (top right corner): with filters; manual focus focusing range (22); flash exposure: +2 1/3......................................................................................................88!

Figure 332: AN1954.25: normal; manual focus focusing range (30); flash exposure: +2 1/3..........................................................................................................................................89!

Figure 333: AN1954.25: with filters; manual focus focusing range (30); flash exposure: +2 1/3. ...................................................................................................................................89!

Figure 334: AN1954.25 (upper half): normal; manual focus focusing range (18); flash exposure: +2 1/3...............................................................................................................89!

Figure 335: AN1954.25 (upper half): with filters; manual focus focusing range (18); flash exposure: +2 1/3...............................................................................................................89!

Figure 336: QCL113: normal; manual focus focusing range (16); flash exposure: +2 1/3.....90!Figure 337: QCL113: with filters; manual focus focusing range (16); flash exposure: +2 1/3.

.........................................................................................................................................90!Figure 338: AN1889.1030: normal; manual focus focusing range (18); flash exposure: +2

1/3. ...................................................................................................................................90!Figure 339: AN1889.1030: with filters; manual focus focusing range (18); flash exposure: +2

1/3. ...................................................................................................................................90!Figure 340: AN1889.1032: normal; manual focus focusing range (25); flash exposure: +2

1/3. ...................................................................................................................................90!Figure 341: AN1889.1032: with filters; manual focus focusing range (25); flash exposure: +2

1/3. ...................................................................................................................................90!Figure 342: AN1893.1-41(167): normal; manual focus focusing range (20); flash exposure:

+2 1/3. ..............................................................................................................................91!Figure 343: AN1893.1-41(167): with filters; manual focus focusing range (20); flash

exposure: +2 1/3...............................................................................................................91!Figure 344: AN1893.1-41(114): normal; manual focus focusing range (20); flash exposure +2

1/3. ...................................................................................................................................91!Figure 345: AN1893.1-41(114): with filters; manual focus focusing range (20); flash

exposure +2 1/3................................................................................................................91!Figure 346: AN1893.1-41(114): normal; manual focus focusing range (20); flash exposure:

+2 1/3. ..............................................................................................................................92!Figure 347: AN1893.1-41(114): with filters; manual focus focusing range (20); flash

exposure: +2 1/3...............................................................................................................92!

!


Figure 348: Blue painted pottery fragments: normal; manual focus focusing range (15); flash exposure: +2 1/3...............................................................................................................92!

Figure 349: Blue painted pottery fragments: with filters; manual focus focusing range (15); flash exposure: +2 1/3......................................................................................................92!

Figure 350: AN1894.107A: normal; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................................................................................93!

Figure 351: AN1894.107A: with filters; manual focus focusing range (20); flash exposure: +2 1/3. ...................................................................................................................................93!

Figure 352: AN1894.107A (upper detail): normal; manual focus focusing range (20); flash exposure: +2 1/3...............................................................................................................93!

Figure 353: AN1894.107A (upper detail): with filters; manual focus focusing range (20); flash exposure: +2 1/3......................................................................................................93!



Figure 356: AN1936.662 (west wall: Amun-Re): normal; manual focus focusing range (25); flash exposure: +2 1/3......................................................................................................94!

Figure 357: AN1936.662 (west wall: Amun-Re): normal; manual focus focusing range (25) flash exposure: +2 1/3......................................................................................................94!

Figure 358: AN1936.661 (west wall: Amun-Re’s headdress): normal; manual focus focusing range (25); flash exposure: +2 1/3. ..................................................................................94!

Figure 359: AN1936.661 (west wall: Amun-Re’s headdress): with filters; manual focus focusing range (25); flash exposure: +2 1/3. ...................................................................94!

Figure 360: AN1936.661 (west wall: Amun-Re’s upper body): normal; manual focus focusing range (25); flash exposure: +2 1/3. ...................................................................95!

Figure 361: AN1936.661 (west wall: Amun-Re’s upper body): with filters; manual focus focusing range (25); flash exposure: +2 1/3. ...................................................................95!

Figure 362: AN1936.661 (west wall: Amun-Re’s arms): normal; manual focus focusing range (25); flash exposure: +2 1/3. ..................................................................................95!

Figure 363: AN1936.661 (west wall: Amun-Re’s arms): with filters; manual focus focusing range (25); flash exposure: +2 1/3. ..................................................................................95!

Figure 364: AN1936.661 (west wall: Amun-Re’s leg): normal; manual focus focusing range (25); flash exposure: +2 1/3. ............................................................................................95!

Figure 365: AN1936.661 (west wall: Amun-Re’s leg): with filters; manual focus focusing range (25); flash exposure: +2 1/3. ..................................................................................95!

Figure 366:AN1936.661 (west wall: Amun-Re’s foot): normal; manual focus focusing range (25); flash exposure: +2 1/3. ............................................................................................96!

Figure 367: AN1936.661 (west wall: Amun-Re’s foot): normal; manual focus focusing range (25); flash exposure: +2 1/3. ............................................................................................96!

Figure 368: AN1936.661 (west wall: Anukis Nethy’s upper body and head): normal; manual focus focusing range (25); flash exposure: +2 1/3...........................................................96!

Figure 369: AN1936.661 (west wall: Anukis Nethy’s upper body and head): with filters; manual focus focusing range (25); flash exposure: +2 1/3. .............................................96!

Figure 370: AN1936.661 (west wall: Satis’s upper body and head): normal; manual focus focusing range (25); flash exposure: +2 1/3. ...................................................................96!

Figure 371: AN1936.661 (west wall: Sati’s upper body and head): with filters; manual focus focusing range (25); flash exposure: +2 1/3. ...................................................................96!

Figure 372: AN1936.661 (west wall: Anukis Ba’s upper body and head): normal; manual focus focusing range (25); flash exposure: +2 1/3...........................................................97!

!


Figure 373: AN1936.661 (west wall: Anukis Ba’s upper body and head): normal; manual focus focusing range (25); flash exposure: +2 1/3...........................................................97!

Figure 374: AN1936.661 (east wall: Taharqa’s upper body and head): normal; manual focus focusing range (25); flash exposure: +2 1/3. ...................................................................97!

Figure 375: AN1936.661 (east wall: Taharqa’s upper body and head): with filters; manual focus focusing range (25); flash exposure +2 1/3............................................................97!

Figure 376: AN1936.661 (east wall: Amun-Re’s upper body and head): normal; manual focus focusing range (25); flash exposure: +2 1/3. ...................................................................97!

Figure 377: AN1936.661 (east wall: Amun-Re’s upper body and head): with filters; manual focus focusing range (25); flash exposure: +2 1/3...........................................................97!

Figure 378: AN1936.661 (east wall: Mut’s upper body and head): normal; manual focus focusing range (25); flash exposure: +2 1/3. ...................................................................98!

Figure 379: AN1936.661 (east wall: Mut’s upper body and head): with filters; manual focus focusing range (25); flash exposure: +2 1/3. ...................................................................98!

Figure 380: AN1936.661 (east wall: Konshu’s upper body and head): normal; manual focus focusing range (25); flash exposure: +2 1/3. ...................................................................98!

Figure 381: AN1936.661 (east wall: Konshu’s upper body and head): with filters; manual focus focusing range (25); flash exposure: +2 1/3...........................................................98!

Figure 382: AN1936.661 (east wall: Montu’s upper body and head): normal; manual focus focusing range (25); flash exposure: +2 1/3. ...................................................................98!

Figure 383: AN1936.661 (east wall: Montu’s upper body and head): with filters; manual focus focusing range (25); flash exposure: +2 1/3...........................................................98!

Figure 384: AN1936.661 (north wall): normal; manual focus focusing range (50); flash exposure: +2 1/3...............................................................................................................99!

Figure 385: AN1936.661 (north wall): with filters; manual focus focusing range (50); flash exposure: +2 1/3...............................................................................................................99!


Figure 387: AN1971.994: with filters; manual focus focusing range (30); flash exposure: +2 1/3. ...................................................................................................................................99!

Figure 388: ANLOAN109.1: normal; manual focus focusing range (50); flash exposure: +2 1/3. .................................................................................................................................100!

Figure 389: ANLOAN109.1: with filters; manual focus focusing range (50); flash exposure: +2 1/3. ............................................................................................................................100!

Figure 390: Michaelis.77, Michaelis.4: normal; manual focus focusing range (30); flash exposure: +2 1/3.............................................................................................................100!

Figure 391: Michaelis.77, Michaelis.4: with filters; manual focus focusing range (30); flash exposure +2 1/3..............................................................................................................100!

Figure 392: Michaelis.43: normal; manual focus focusing range (20); flash exposure: +2 1/3........................................................................................................................................100!

Figure 393: Michaelis.43: with filters; manual focus focusing range (20); flash exposure: +2 1/3. .................................................................................................................................100!

Figure 394: Michaelis.111: normal; manual focus focusing range (30); flash exposure: +2 1/3. .................................................................................................................................101!


Figure 396: Michaelis.225: normal; manual focus focusing range (30); flash exposure: +2 1/3. .................................................................................................................................101!


!





Figure 401:Michaelis.31: with filters; manual focus focusing range (28); flash exposure: +2 1/3. .................................................................................................................................102!

Figure 402: AN1947.270: normal; manual focus focusing range (30); flash exposure: +2 1/3........................................................................................................................................102!

Figure 403: AN1947.270: with filters; manual focus focusing range (30); flash exposure: +2 1/3. .................................................................................................................................102!







Figure 410: AN1888.1178: normal; manual focus focusing range (18); flash exposure: +2 1/3. .................................................................................................................................104!


Figure 412: AN1890.756 (=AN1963.2): normal; manual focus focusing range (18); flash exposure: +2 1/3.............................................................................................................105!

Figure 413: AN1890.756 (=AN1963.2): normal; manual focus focusing range (18); flash exposure: +2 1/3.............................................................................................................105!





Figure 418: Composite of images taken of Amun-Re on the west wall of AN1936.661. .....112!

!


Chapter 1: INTRODUCTION

1.1 Egyptian Blue !

1.1.1 What is Egyptian blue? Egyptian blue is the earliest synthetic pigment and was created to make up for the lack

of a readily available and stable blue pigment in ancient times (Berke, 2002: 2483). It has

been called many names over the years but remained chemically the same: iryt (Delamare,

2000: 20), kyanos, caeruleum (Nicholson with Peltenberg, 2000: 178), Pompeian blue,

Vestorian blue, bleu fritte, bleu d’Alexandrie, bleu de Pompei, bleu de Pouzzoles, azzuro

egiziano, Frittenblau, and Egyptian blue (Riederer, 1986: 23). It can be different shades of

blue depending on the composition: a diluted light blue which is high in alkali and contains a

large proportion of glass, a light blue which is low in alkali with small crystals of cuprorivaite

mixed with other components, or a dark blue which is low in alkali with coarse crystals of

cuprorivaite (Lee and Quirke, 2000: 109).

Egyptian blue was the first ancient material to be examined by modern scientists: Sir

Humphrey Davy examined a small pot from Pompeii in 1814; Fouque analysed it and

concluded that it consisted of the calcium-copper tetrasilicate CaCuSi4O10, or cuprorivaite

(Pradell et al, 2006: 1426). Since then this formula has been used by Accorsi et al (2009:

3393), Berke (2002: 95), Bourherour et al (2001: 947), Pradell et al (2006: 1426), Tilley

(2011: 297), and others to represent Egyptian blue.

While this formula is generally accepted, there are a number of scholars who believe

that Egyptian blue also contains other elements. For example, El Goresy et al state that Old

Kingdom Egyptian blue contained a minor amount of wollastonite (CaSiO3) and Wiedemann

et al (1998: 195) agree, stating that in all artefacts they tested Cu-bearing wollastonite was

present in the pigment. This has implications on the study of Egyptian art and materials if it is

true, but a later study by Bourherour et al (2001: 947) disagrees with this statement due to the

lack of any wollastonite detected in their Raman spectroscopy study which would have

detected it. Bianchetti et al (2000: 179) argue that Egyptian blue is a mixture of cuprorivaite,

silica phase (quartz, tridymite and cristobalite), cuproan alkali and chlorine-bearing silicate

glass, and a copper oxide phase. Finally, Lucas (1962: 340-341) suggests that natron was

heated together with the silica, copper, and calcium carbonate, as reported by Vitruvius.

!


The disagreements between scholars on the exact chemical makeup of the pigment

might be attributable to a reliance of each study on a particular subset of Egyptian blue

objects, as it is very likely that at different places and times the mixture of phases present in

the pigment would differ slightly. Also, a firm conclusion may be unreachable due to the long

period of time that the pigment was in use and the fact that it came to be manufactured in

many different places. As with any manufactured item, recipes can easily be adapted and

changed depending on what materials were available to the person making it, so it is entirely

possible for a whole range of artefacts to either have, or not have, certain elements present.

Chemically, Egyptian blue is a multiphase material and is described by Lee and Quirke

(2000: 108) as an “anhydrous sheet silicate containing unbranched, single layers with four-

membered rings (Si4O12)”. The basic silicate complex is symmetry four, with each silica

tetrahedra corner-linked by oxygen bound to copper in square coordination; for each

tetrahedron, one oxygen atom belongs to an neighbouring four-membered unit (Tilley, 2011:

297).

Egyptian blue is soluble in boiling hydrochloric acid (Weber, 1924: 53) but in general,

it is a very stable pigment that is largely resistant to strong light even after thousands of

years. Some discolouration has been noted by Daniels et al (2003: 4) which may have been

caused by the coarse grains of the pigment trapping dirt, or it might be due to a crust of

calcium sulphate that formed over the layer of pigment. Another reason for the sometimes

observed discolouration could be because of devitrification of the interstitial glass in the

pigment which might cause the pigment to become soft and friable (Green, 2001: 44).

Discolouration or devitrification, however, do not affect the chemical structure of Egyptian

blue and as such, should not interfere with the current study.

1.1.2 Why it emits luminescence !

Luminescence is the observable fact of emission of electromagnetic radiation in the IR

or UV region in excess of thermal radiation (Williams, 1966: 2). Egyptian blue, or

cuprorivaite, has luminescent properties resulting from the Cu2+ ion being located in a

symmetrical tetrahedral environment which makes it subject to Jahn–Teller distortion

(Warner, 2011: 30). This causes an octahedral to tetragonal symmetry shift, and the t2g and eg

orbitals to split in such a way that room is made for the light used to induce luminescence

(Bredal-Jorgensen et al, 2011: 1437).

!


Following excitation in the IR region at 800 nm, the broad IR emission band will be

centred around 950 nm, which indicates that the single optically active cause of energy

absorption in the visible range is the Cu2+ ion (Pozza et al, 2000: 395). This energy

absorption in the IR region of the electromagnetic spectrum causes an electron to be

promoted from lower energy levels in the d-shell to the dx2

-y2 level on the Cu2+ ion; the band

maxima yield the following values expressed in terms of decreasing wavelength: l1 (2B1g -> 2B2g) = 800nm; l2 (2B1g -> 2Eg) = 630 nm; and l3 (2B1g -> 2A1g) = 540nm (Warner, 2011: 30-

31).

These three electronic transitions indicate that the Jahn-Teller effect on the Cu2+ ion is

considerable, and as such, the pigment will not absorb blue and violet wavelengths; as

humans are more sensitive to blue colours, the pigment, therefore, appears blue in visible

light (Warner, 2011: 31-32).

The luminescence of copper-activated glasses is an expected phenomenon since copper

is often introduced to glass to stabilize the Cu2+ and give it a blue colour (Rindone, 1966:

427). However, not all copper-activated blue glass has the same luminescent properties as

Egyptian blue and will react the same when photo-induced luminescence digital imaging is

used since they will have different emission peaks and would only be detected with specific

filters in place.

1.1.3 How it was made

Over the 4000-year period that Egyptian blue was in use, its manufacture and

composition have been proved by archaeometric measurements to be fairly consistent (Berke,

2002: 2485). Raw material, lumps from furnaces, and ground pigment have been analysed

and found to contain the same basic composition which suggests that the selection of

materials and the manufacturing process was known to be important (Russell, 1893: 3).

Although written evidence of this manufacturing process has yet to be discovered, physical

evidence was discovered at a workshop in Qantir-Pi-Ramesse dating to 1650-1550 BCE

wherein ceramic crucibles with cuprorivaite crystals on their inner surfaces were uncovered

(Warner, 2011: 35). Though it is still not known how the manufacturing process stayed

consistent over the years and places that Egyptian blue was produced, this archaeological

evidence of production is vital information.

This manufacturing process included mixing together sources of silica, calcium, and

copper: the silica was usually in the form of sand, since sand was easily accessible and

!


usually contained quartz and calcium carbonate (Lucas and Harris, 1962: 341; Nicholson

with Peltenburg, 2000: 186); the calcium was usually in the form of limestone; and the

copper may have been in the form of copper alloy filings, bronze fragments, or malachite

(Daniels et al, 2003: 2; Edreira et al, 2003: 29; Lluveras et al, 2010: 316; Berke, 2002: 2485;

Warner, 2011: 26). Most known production methods of Egyptian blue include the use of a

salt or plant ash flux (Lluveras et al, 2010: 316); the reactants (CaO, CuO, and SiO2) partially

dissolve and then exsolve as crystalline CaCuSi4O10 while still at a high temperature of

around 800-900° C before slowly cooling (Warner, 2011: 26). This process has been intuited

not just through archaeological evidence, but through modern scientists attempting to

replicate the same results that were obtained in the ancient world.

Temperature control is very important to the process since the pigment decomposes at

1000° C to a mixture of copper oxide, tridymite, and glass; this was likely the cause of the

development of sintering techniques for producing items such as amulets, seals, or bricks

since casting was not possible (Berke, 2002: 2485). The temperature of the furnace was never

high enough to fully fuse the elements together which left a semi-fused frit that could later be

powdered and heated again to develop the blue further (Laurie et al, 1914: 419).

Based on results from modern experiments, it seems likely that Egyptian blue would

have either been fired a single time in order to produce a coarse-textured frit that could be

crushed into a deep, dark blue pigment, or fired a second time to produce a more finely

textured bright blue pigment (Tite et al, 1998: 113).

The process developed over time: flux additives, such as papyrus ash which consisted

of K2CO3, improved the quality; the introduction of air necessary to the process improved

from the use of pipes to manually blow air into the use of bellows; and from the 18th Dynasty

tin oxide (SnO2) became universally used in the pigment’s production whereas before it was

absent (Berke, 2002: 2485; Warner, 2011: 38).

Although the manufacturing process and recipe changed slightly depending on which

materials were available at the time and place of production, the basic components of silica,

calcium, and copper remained the same. This base formula present in all Egyptian blue

samples is useful to the current study as it means that the chemical structure of the pigment

remains unchanged and therefore the pigment will react to luminescence-inducing light in an

expected way.

!


1.1.4 How it was used

Egyptian blue was used as a pigment on canvas, papyrus, plaster, pottery, wall

paintings, wood (Riederer, 1986: 23), and sculptures (Bredal-Jorgensen et al, 2011: 1433); it

was also used as a material to form into compact blue art objects such as beads, figurines,

rings, scarabs, and bowls, and in the production of faience (Tite et al, 1998: 111; Berke and

Wiedemann, 2000: 22). The pigment has been found throughout history in different forms: as

decoration in the ruined Sun Temple at Abu Gurob and in Per-Neb’s tomb at Giza in the 5th

Dynasty; as cylinder seals in the 6th Dynasty; as inlays in a gold bracelet from Dur Kurigalzu

in the Kassite period; as imported vessels after the technological Dark Age of 1200-900 BCE

at Hasanlu; and as small objects of solid blue frit from the 18th Dynasty (Moorey, 1994: 187;

Lucas, 1962: 343).

Egyptian blue was important to the decoration of wooden mummy coffins as well

which were layered with Nile mud and pigments, including Egyptian blue, to create an image

of the deceased (Berke and Wiedemann, 2000: 22). The prominence of Egyptian blue on

coffins might be because Egyptians believed that the hair of divine beings consisted of lapis

lazuli and, as such, used blue hair to illustrate the transition of the deceased to the world

beyond (Taylor, 2001: 167). Since lapis lazuli was not readily available in ancient Egypt,

Egyptian blue would have been used in its place to symbolise the mineral.

Egyptian blue was used to symbolise more than just lapis lazuli. In fact, all samples of

painted green stone surfaces from the Old and Middle Kingdom have been tested and proved

to be predominantly Egyptian blue with small amounts of green copper; this is likely because

it was not until the New Kingdom that green frit was developed and the green component of

copper wollastonite outweighed the component of cuprorivaite (Lee and Quirke, 2000: 110).

This means that any time Egyptian artists wanted to portray something green, Egyptian blue

would have been used instead, most likely causing the manufacturing process for the pigment

to be refined even more, showing the careful attention Egyptian artists must have paid to the

exact recipe of the pigment.

In addition to the various ways it was used as a pigment, the frit was also powdered and

added to water to make a paste used to mold into small objects such as beads and amulets

which could be dried and fired (Hodgson, 1936: 36-38). Scarabs and small objects made of

Egyptian blue have been found particularly throughout the eastern Mediterranean dating from

the eighth to sixth centuries BCE; when found in Egypt, these items tend to appear in areas

where there is evidence of a predominantly foreign population (Moorey, 1994: 188). The

!


objects themselves may have been seen as trade-worthy, or it might have been the rather rare

blue pigment that caused these objects to be traded. Either way, it appears that the Egyptians

themselves mostly used the pigment for painting and not for molding, perhaps due to the

symbolism inherent in the colour blue.

Although the pigment was seemingly commonly used, it does not appear to have been

very easy to use. If the grain size of the pigment was reduced to make it fine enough for

detailed decoration, the pigment would become very diluted and pale, so instead it had to be

kept quite thick with a large grain sized which then got pressed, rather than smoothly

brushed, into place (Daniels et al, 2003: 2-3). This may have been quite limiting, but the fact

that Egyptian blue was used for many years and in many different ways regardless suggests

that it was an important pigment and had high value even just as the sole source of blue

pigment available. This explains why a pigment of rather low quality remained in use over

such a long period of time and large area of land.

There has thus far been no evidence of the application of natural blue pigments

(malachite, azurite, or chrystocolla) to Egyptian monuments during the Egyptian period (up

until 37 CE) perhaps because they were not as stable as Egyptian blue was (El Goresy et al,

1986: 7). This may have been due to the expense of other blue pigments, since lapis lazuli

later became available through trade to Egypt and was still not used, or simple preference.

In later years, Egyptian blue was used in slightly different ways in England as part of

polychrome sculptures, and in continental Europea as part of wall paintings (Gaetani, 2004:

14).

1.1.5 When it came in and out of use

Egyptian blue was the most frequently used blue pigment in all of Europe from its

invention until the end of the Roman period, after which time other blue pigments began to

be used and the ability to produce Egyptian blue was gradually lost (Edreira et al, 2003: 29).

There is not an agreed upon date for when Egyptian blue was invented, but most

scholars agree that it began to be used around the 4th Dynasty (Lucas, 1962: 342; Spurell,

1895: 227; Laurie, 1913: 317; Smith and Plantzos, 1946: 256). However, Chiari and Scott

(2004: 230) argue that the pigment “was widely used throughout the Ancient Middle East,

starting from about 3600 BC, when it was first synthesized” which is significantly earlier

than the 4th Dynasty. Mirti et al (1995: 437) concur that the pigment may have been

developed earlier in Mesopotamia than the generally accepted date for development in Egypt.

!


The earliest surviving use of Egyptian blue was discovered on a painting from Tomb 3121 at

Saqquara dated to 2900 BCE (Hatton et al, 2008: 1591), but it is believed that the pigment

did not become more widely used until the 4th Dynasty (2600-2480 BCE), and did not reach

the height of use until the New Kingdom period (1580-1085 BCE) which was during the peak

of Egyptian art production in general (Berke, 2002: 2483).

During the height of the pigment’s use, it is probable that the knowledge of Egyptian

blue’s production process spread to China either by trade, or with merchants and

knowledgeable individuals along the road later known as the Silk Road (Berke, 2002: 114).

This timeline aligns with the 800 BCE date of the earliest examples of Han blue and Han

purple (Berke, 2006: 28); the pigments are so similar in composition to Egyptian blue that it

is conceivable that the knowledge of Egyptian blue was in China before 800 BCE and was

used as a template to create Han blue and Han purple.

During the Graeco-Roman period the extensive production of Egyptian decorative

objects decreased in number, but Egyptian blue still remained the choice blue pigment when

objects with blue pigment were produced (Riederer, 1986: 25). In fact, Riederer (1986: 25-

26) posits that the production of Egyptian blue was introduced to Crete and the other Greek

islands from Egypt immediately after the pigment’s invention due to the evidence of

Egyptian blue from 2100 BCE in wall paintings at Knossos; it continued to be used in the

Mycenean period (thirteenth century BCE) in such examples as the House of Idols and the

Temple of Mycenae. In Greece, Egyptian blue was mostly used for wall paintings and

façades, such as the façade of the earlier temple of Aphaia at Aegina (sixth century BCE),

and it continued to be used throughout the Greek period in Greece (Riederer, 1986: 25-26). It

was possibly mentioned by Theophrastus (371-287 BCE) as an artificial blue pigment traded

from Egypt, indicating that it was produced in Egypt until that relatively late period and

continued to be traded (Riederer, 1986: 26) with the rest of the Mediterranean. In support of

this, production debris resulting from the production of Egyptian blue have been found at

Memphis, near Cairo dating from the third century BCE to the third century CE (Hatton et al,

2008: 1592).

According to Vitruvius and Pliny, the production of Egyptian blue in Roman Italy

began most likely not long before the first century CE (Lee and Quirke, 2000: 111).

However, there are numerous archaeological examples of Egyptian blue used on wall

paintings and tombs by the Etruscans in Italy from around the sixth century BCE (Riederer,

1986: 26), which could indicate that Egyptian blue was produced by the Etruscans before the

Romans began producing it, or that it was traded to the Etruscans by the Phoenicians.

!


Egyptian blue mostly faded from use after the Roman Empire fell in 500 CE, but over

the following few centuries it reappeared a few times (Warner, 2011: 40). Riederer (1986: 27)

states that Isidore of Sevilla was the author of the latest literature reference to Egyptian blue

in 636 CE, which Lluveras et al (2010: 318) use to argue that the production process of

Egyptian blue was lost in the Mediaeval period.

However, there are archaeological examples of wall paintings past this date with lapis

lazuli sometimes also present, showing that the shift to a preference for lapis lazuli was

gradual. Lapis lazuli was quite expensive at this time, so Egyptian blue may have continued

to be used for the express purpose of reducing the cost of blue pigments to artists by mixing

the two together (Bredal-Jorgensen et al, 2011: 1438). The San Saba paintings at Rome have

been dated to the first half of the eighth century CE and contain a clear use of both pigments,

showing that by this date the process of how to purify the lapis lazuli ore was known (Gaetani

et al, 2004: 20). Although lapis lazuli was known by this time, Egyptian blue continued to be

used in continental Europe.

The San Clemente church in Rome yielded the ninth century CE Ascension which

contains a poor quality Egyptian blue, perhaps indicating the artist used a Roman-era

Egyptian blue frit, or that still-active, oriental painter-monks from Rome may have traded the

pigment, demonstrating that the Egyptian blue making process had not been completely

forgotten (Lazzarani, 1982: 85).

Carolingian wall paintings in Müstair also of the ninth century CE have been found to

contain Egyptian blue (Llueveras et al, 2010: 318). Very late occurrences of Egyptian blue

include the eleventh or twelfth century CE Last Judgment, signed by Roman artists Nicolo

and Giovanni, and the thirteenth century CE Loggia dei Cavalieri at Treviso (Gaetani et al,

2004: 19). A final example of Egyptian blue has been found by Bredal-Jorgensen et al (2011:

1438) in a painting by Giovanni Battista Benvenuto in 1524 CE in which the dress of St.

Margaret contains ultramarine mixed with Egyptian blue; although an unusual combination,

the paintings were ruled legitimate due to strong provenance and the extent of the

luminescence of the pigment.

It is possible that the Egyptian blue pigment being used in medieval creations and

restorations were Roman-era pigments being reused; this is likely the case for the Sant Pere

altarpiece (dated to the twelfth to fourteenth centuries CE) since the church was very near to

the Roman town of Egara (Lluveras et al, 2010: 309, 318). At this time it is impossible to say

if the Egyptian blue found in paintings such as these were manufactured contemporarily, or if

they were reused; further work could prove either way. If they were reused, it would be worth

!


asking why they were used if contemporary blue pigments were available and of better

quality.

After these last few examples, however, the pigment was apparently out of use until

Chaptal rediscovered the pigment in the nineteenth century CE at Pompeii (Warner, 2011:

40). After this, the pigment began to be examined and recorded, and the process of how to

make Egyptian blue was rediscovered as scholars’ interest in the pigment grew.

1.2 Previous work on this technique !

1.2.1 What equipment was used and how it was used

Previous work has been done by G. Verri (2009a, 2009b) on the photo-induced

luminescence digital imaging of Egyptian blue, Han blue, and Han purple, with a set up

including an excitation source, a recording device, and an emission filter. He has tested his

technique on objects known to contain Egyptian blue, and on objects where the presence of

each pigment was not known; all tests were run in complete darkness.

As an excitation source, Verri used two identical radiation sources, either LED,

fluorescent, tungsten-halogen, or UV, that were oriented approximately 45° to the focal axis

of the camera, allowing even distribution of the excitation source (Verri, 2009b: 1013).

For LED sources, Verri tested a blue LB300B by Excled, a green LB300G by Excled, a

red LB300R by Excled, and a yellow LB300Y by Exled (Verri, 2009b: 1014).

For fluorescent sources, Verri tested a cool white Dulux 36W 12-950 by Osram, a

daylight TLD/865 Super80 by Philips, a daylight LT58W/760-101 by Navara, a warm white

Philips TLD 58W/35 by Philips, a warm white MASTER TLD 58W/840 Super 80 by Philips,

a warm white Sylvania F58W/29-530 by Sylvania, a warm white de luxe F58W/830 by

Sylvania, a white F58W/35-535 by Sylvania, a blue LT58W/018 by Navara, a green

LT58W/017 by Navara, a red LT58W/015 by Navara, and a yellow LT58W/016 by Navara

(Verri, 2009b: 1014).

For a tungsten-halogen source, Verri tested a white-yellow DXX 800W by Osram, and

for a UV source, Verri tested a non-visible F8T5BLB by Philips (Verri, 2009b: 1014).

To record the luminescence emission during the tests for each type of excitation source,

Verri used a modified Canon 40D camera with its inbuilt IR-blocking filter removed, giving

it a sensitivity between 350 and 1000 nm (Verri, 2009a: 2). This allowed stray IR radiation

from the sample in this spectral range to be recorded by the camera.

!


A Schott RG830 filter with a 50% cut-on at 830 nm was placed in front of the lens to

limit the spectral range from the filter’s cut off at 800 nm to the camera’s built in sensitivity

at 1000 nm (Verri, 2009b: 1013). In this way, the camera was modified to only allow

luminescence and stray IR radiation between 800 nm and 1000 nm to be detected and

recorded by the camera.

Finally, a set of Lambertian reference grey scales by Labsphere were used to compare

the presence of luminescence since they have certified flat reflectance properties in the UV-

VIS-IR spectral range and therefore do not display luminescence (Verri, 2009b: 1013). In this

way they acted as a control to test against. The equipment’s arrangement can be seen in

Figure 1, and the camera’s settings were kept the same throughout the experiment (Verri,

2009a: 1013).

Figure 1: Schematic representation of the experimental setup used for visible-induced luminescence

imaging of Egyptian blue (Verri, 2009a: 3).

The radiation sources were activated and aimed at the pigment samples. They were

partly absorbed by the luminescent pigments and partly re-emitted as IR radiation that was

reflected, transmitted, or absorbed depending on the optical properties of the pigments being

tested; this radiation was blocked by the RG830 filter on the camera lens, and the camera’s

digital sensor recorded the luminescence and reflected stray IR radiation to produce a photo-

induced luminescence image in the IR range (Verri, 2009b: 1014-1015).

!

!

!"#$%&'!()! *+,'-./#+! &'0&'*'1/./#21!23! /,'! '40'&#-'1/.5! *'/%0!%*'6! 32&! 7#*#85'9#16%+'6! 5%-#1'*+'1+'! #-.$#1$!23!:$;0/#.1!

85%'<!

!"#$%&"'()

!"#$%&'()$*+,%

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

*+! ,-.-)-/,)01234.2).5$)(67#%"8#&9:)9;)(#%"<)=0)%">&"#&9:)

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

U1! 2&6'&! /2! *%8/&.+/! /,'! */&.;! UF! &.6#./#21@! .! -'.*%&'-'1/! #*! -.6'! 23! /,'! &'35'+/#7'! 0&20'&/#'*! 23! /,'! *%&3.+'! %16'&!#17'*/#$./#21!8;!#1*'&/#1$!.!]]^!&'35'+/.1+'!*/.16.&6!#1!/,'!0,2/29#16%+'6!5%-#1'*+'1+'!#-.$'<!=,'!-'.*%&'-'1/!23!/,'!&'35'+/#7'! 0&20'&/#'*! 23! 5%-#1'*+'1/! 0#$-'1/*! #*! #1! $'1'&.5! .! /.*?! 3&.%$,/! >#/,! /'+,1#+.5! 6#33#+%5/#'*_! #1! /,'! +.*'! 23!+%0&2&#7.#/'@! /,'! '4+#/./#21! *0'+/&%-! 27'&5.0*! 0.&/#.55;! >#/,! /,'! '-#**#21! *0'+/&%-! V`X<! A2>'7'&@! .1! .00&24#-./'!'*/#-./#21!23!/,'!&'35'+/#7'!0&20'&/#'*!+.1!8'!.+,#'7'6!%*#1$!/%1$*/'1!*2%&+'*!3#5/'&'6!>#/,!.!I+,2//!FMBaC!$5.**!3#5/'&<!U1!/,#*! &.1$'!QBCC9(CCC!1-S!23! /,'!'5'+/&2-.$1'/#+!*0'+/&%-!/,'!.8*2&0/#21!8;! /,'!0#$-'1/! #*!+21*#6'&.85;!*-.55'&! /,.1!/,./!#1!/,'!&'6!&.1$'<!U/!*,2%56!8'!12/'6!/,./@!8'+.%*'!23!/,'!5%-#1'*+'1+'!'-#//'6!8;!/,'!0.&/#+5'*!23!:$;0/#.1!85%'@!/,'!%*'! 23! %13#5/'&'6! /%1$*/'1! &.6#./#21! *2%&+'*! 32&! /,'! +,.&.+/'&#b./#21! 23! /,'! &'35'+/#7'! 0&20'&/#'*! 23! /,'! 0#$-'1/! #*! 12/!.00&20&#./'<! T,'1! %13#5/'&'6! /%1$*/'1! &.6#./#21! *2%&+'*! .&'! %*'6@! /,'! 7#*#85'! +2-021'1/! '-#//'6! 8;! /,'! *2%&+'*! #*!.8*2&8'6!.16!0.&/#.55;!&'9'-#//'6!8;!/,'!0#$-'1/!.*!UF!&.6#./#21<!E**%-#1$!.!,2-2$'1'2%*!6#*/&#8%/#21!23!/,'!#1+2-#1$!#55%-#1./#21! .16! /,'! 5#1'.&#/;! 23! /,'! &'+2&6#1$! 6'7#+'@! /,'! *%8/&.+/#21! 23! /,'! */&.;! UF! &.6#./#21! +.1! 8'! %16'&/.?'1! 8;!32552>#1$!/,'!*/'0*!5#*/'6!8'52>)!

!"#$%&#'&(!)*&+#,%&-./0&&-./0123.

Downloaded From: http://proceedings.spiedigitallibrary.org/ on 01/24/2013 Terms of Use: http://spiedl.org/terms

!


1.2.2 What results were obtained

Verri’s technique obtained good results, and showed that Egyptian blue, Han blue, and

Han purple showed strong luminescent properties in the 800-1000 nm range when excited in

the visible range and recorded by a modified camera (Verri, 2009a: 11). Figure 2 shows the

blue pigments Verri tested with the three pigments in question on the bottom row. As can be

seen, in the 800-1000 nm range, only the three pigments in question show strong

luminescence signatures; however, in the 800-1700 nm range, manganese blue displays

similar luminescent properties (Verri, 2009a: 6).

Figure 2: a) visible RCB image of the blue pigments; b) red-induced luminescence image in the 800-

1000 range; c) red-induced luminescence in the 800-1700 range (Verri, 2009a: 6).

Each radiation source had slightly different results, with some having better results than

others. Verri recommends using LED sources initially, to be potentially followed by

fluorescent sources (Verri, 2009b: 1016). A summary of the results of each radiation source

follows:

Each type of LED excitation source tested succeeded in exciting an intense

luminescence in the Egyptian blue, Han blue, and Han purple with a high spatial resolution of

the camera (Verri, 2009b: 1015). This excitation source enables a user to straightforwardly

discriminate between various blue pigments of different provenance and age as the difference

between the reactions of the three pigments in question and the other blue pigments is so

clear (Verri, 2009b: 1016).

Fluorescent sources emitted some luminescence in the IR range, but the emission was

quite weak compared to the emission present in the visible range (Verri, 2009b: 1015).

Verri’s experiment confirmed that fluorescent lamps emit stray IR radiation which made the

other blue pigments he tested appear to fluoresce; however, when compared to the 99%

reference grey standard, Egyptian blue and Han purple levels were higher than that of the

stray IR radiation present, showing why the reference grey standard was so important for

!

!

!"#$%! &'! ()! *#+#,-.!/01! #2($.! 34! 56.! ,-7.! 8#$2.95+! :.+;<#,.:! (,3*.%!=(9!,-7.>!=(9!87<8-.! (9:!?$@85#(9! ,-7.! (<.! #9! 56.!

,35532!<3AB!,)!<.:C#9:7;.:!D�.E;!F!GHI!92)!-72#9.+;.9;.!#2($.!#9!56.!JKKCLKKK!92!<(9$.%!M6.!56<..!8#$2.95+!+63A!(9! #95.9+.! -72#9.+;.9;.! #9! 56#+! <(9$.B! ;)! <.:C#9:7;.:! D�.E;! F! GHI! 92)! -72#9.+;.9;.! #9! 56.! JKKCLNKK! 92! <(9$.%! O9!(::#5#39!53!56.!56<..!8#$2.95+!2.95#39.:!(,3*.>!2(9$(9.+.!,-7.!D<#$65>!2#::-.!<3A)!+63A+!-72#9.+;.9;.!8<38.<5#.+%!

!

!"! #$%&#'()(*+%#),%#-',-./0+'-,!

MA3!;(+.!+57:#.+!4<32!56.!;3--.;5#39+!34!56.!1<#5#+6!P7+.72!(<.!#9;-7:.:!6.<.!53!#--7+5<(5.!56.!7+.!34!56#+!5.;69#Q7.>!,356!39!8(#95#9$+!34!56.!R9539#9.!8.<#3:!DRS!LKKCHKK)%!

12345,678982:9;<,M6.!4#<+5!;(+.!+57:@!8<.+.95.:!6.<.!#+!34!2722@!83<5<(#5+!4<32!56.!$<378!345.9!5.<2.:!56.!T"(@72!83<5<(#5+U%!V6#-.!5<7-@!<.8<.+.95(5#*.!8(#95#9$+!:#:!935!4.(57<.!4<.Q7.95-@!#9!R9;#.95!?$@85#(9!(<5>!56.@!A.<.!;32239!#9!56.!0<.;3C/32(9!A3<-:>!(9:!+5(<5.:!53!(88.(<!#9!?$@85!#9!56.!4#<+5!;.957<@!RS!A6.9!5A3!5<(:#5#39+>!56.!8<.+.<*(5#39!34!56.!,3:@!4<32!86(<(39#;!?$@85!(9:!56.!;322.23<(5#39!34!#9:#*#:7(-+!4<32!0<.;3C/32(9!;39*.95#39!,.;(2.!47+.:!WJX%!P722@! 83<5<(#5+! (<.!2(#9-@! 8(#95.:! 39!A33:! 3<! -#9.9! D56.! 8#.;.+! :#+;7++.:! 6.<.! (<.! 39! -#2.A33:)! (9:! (<.! 7+7(--@!.E.;75.:!7+#9$! 5A3!:#44.<.95! 5@8.+!34!,#9:#9$!2.:#(Y5.28.<(! D.%$%! .$$>! (9#2(-!$-7.+)! (9:! .9;(7+5#;! D,..+A(E)%!M6.!<.+7-5+! 34! 56.! 8<.-#2#9(<@! #9*.+5#$(5#39+! 39! 5A3! 83<5<(#5+! A#--! ,.! <.83<5.:! 6.<.'! (! A32(9! D1<#5#+6!P7+.72! Z72,.<!G[&\G'!!"!RS!LGKCLNK)!(9:!(!,.(<:.:!2(9!A#56!(::.:!$3-:!-.(4!D1<#5#+6!P7+.72!972,.<!N\J&H'!!"!RS!L\KCLJK)B!+..!"#$%!\(!(9:!"#$%![(>!<.+8.;5#*.-@%!1356!83<5<(#5+!(<.!+5@-#+5#;(--@!:(5.:!53!56.!2#:C!3<!-(5.!R9539#9.!8.<#3:!(9:!(<.!,.-#.*.:!53! ;32.! 4<32! .<C/7,(@(5! #9! ?$@85>! (-5637$6! 93! 8<.;#+.! <.;3<:! 34! 56.#<! 8<3*.9(9;.! +7<*#*.+! WJX%! 1356! 8(#95#9$+! (<.!(55(;6.:!53!A33:.9!;<(:-.+!A6#;6!(<.!,.-#.*.:!53!8<.*.95!56.!9(57<(-!23*.2.95!34!56.!3<#$#9(-!+7883<5+!(9:!56.<.43<.!53!,.! :.5<#2.95(-! 53! 56.#<! 86@+#;(-! +5(,#-#5@>! 2(]#9$! 56.2! (! 6#$6! ;39+.<*(5#39! 8<#3<#5@%! M3! (++#+5! #9! #9*.+5#$(5#9$! 56.#<!;39:#5#39!(!8<.-#2#9(<@!+.<#.+!34!#2($.+!6(+!,..9!8<3:7;.:!(;<3++!56.!^_>!*#+#,-.!(9:!O/!+8.;5<72%!,

M6.!*#+#,-.! #2($.!34! 56.!83<5<(#5!34! (!A32(9! D1<#5#+6!P7+.72!Z72,.<!G[&\G)! #+! +63A9! #9!"#$%!\(%!=.<!;-356#9$Y(!87<8-.C,-7.! 579#;!A#56!(!$3-:!!#$%&'(D+5<#8.)!(9:!(!;<.(2@CA6#5.!2(95-.Y#+!+32.A6(5!797+7(-!43<!"(@72!83<5<(#57<.>!A6#-.!6.<!6(#<!#+!.-(,3<(5.-@!A(*.:!(<379:!56.!43<.6.(:!#9!(!5@8#;(-!2#:CR9539#9.!4(+6#39%!`6.!A.(<+!a.A.--.<@!34!+Q7(<.!$<..9! +539.+>!8.(<-+>! (! <.:! <379:! +539.! +.5! #9!$3-:!(9:!(!A<.(56!34!$3-:! -.(*.+%!"#$%!\,! +63A+! 56.!7-5<(*#3-.5C#9:7;.:!-72#9.+;.9;.!D�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email protected]!8#$2.95!D([email protected]!79#:.95#4#.:)%!M6.!#2($.!(-+3!+7$$.+5+!56(5!56.!$<.@!,(;]$<379:>!56.!A6#5.+!34!56.!.@.+!(9:!56.!A6#5.!6#$6-#$65+!34!56.!8.(<-+!(-+3!;395(#9!?$@85#(9!,-7.>!(+!:3!56.!4-.+6!539.+%!V6#-.!56.!;36.<.9;.!34!56.!-#9.!34!?$@85#(9!,-7.!:.4#9#9$!56.!,3<:.<!,.5A..9!56.!+]#9!(9:!56.!6(#<!27+5!2.(9!#5!#+!#95.95#39(->!#5+!7+.! #9! 56.! 4(;.! (9:! -#8+! 27+5! ,.! #95.<8<.5.:! A#56! +32.! ;(75#39%! R-5637$6! 7+7(--@! ;3(<+.-@! $<(#9.:>! ?$@85#(9! ,-7.!

!"#$%&#'&(!)*&+#,%&-./0&&-./01234

Downloaded From: http://proceedings.spiedigitallibrary.org/ on 01/24/2013 Terms of Use: http://spiedl.org/terms

!


Verri’s experiments (Verri, 2009b: 1015). Consequently, this technique can be useful when

trying to locate either Egyptian Blue, Han blue, or Han purple within a large piece of art since

it allows the rest of the pigments to be slightly illuminated (Verri, 2009b: 1016). This will

produce an image that will show the artwork in full, with the pigments in question

highlighted, instead of showing the highlighted pigments against a black background.

The tungsten-halogen source Verri used emitted a significant amount of IR radiation

and any recorded images demonstrate only the reflective behaviour of the pigments, and not

the luminescence properties (Verri, 2009b: 1015-1016). Therefore, tungsten-halogen

radiation sources are not appropriate for this task as the luminescence of Egyptian blue, Han

blue, and Han purple are hidden by high IR background noise (Verri, 2009b: 1016).

The UV source used by Verri did not cause any IR radiation to be emitted and produced

no stray IR emission; Han purple produced a strong luminescence emission, Egyptian blue

produced a slight luminescence emission, and Han blue produced none (Verri, 2009b: 1015).

1.2.3 Suggested further work

Verri noted that in general, Han blue generates a weaker emission than Egyptian blue

and Han purple, and that this behaviour should be investigated further (Verri, 2009b: 1015).

1.2.4 Problems distinguishing between Egyptian blue, Han blue, and Han purple

As Verri (2009a and 2009b) has shown, Egyptian blue, Han blue, and Han purple react

rather similarly under test conditions. They are all macroscopically similar with chemically

related compounds (Berke, 2002: 2484); XRD with elemental analysis would differentiate

them (Riederer, 1986: 40) since the only difference between Egyptian blue and Han blue is

the way they exchange the earth alkali element (Berke, 2006: 20).

This creates potential problems with using photo-induced luminescence digital

imaging; if the three pigments react the same way, the images produced by the experiment

would be only illustrate the presence of either of the three pigments, not which of the three

was present. The materials being tested in this study are very unlikely to contain either Han

blue or Han purple, but future testing may encounter difficulties, and as such, this technique

should only be used as an initial surveying tool before further testing is completed.

!


1.3 Materials

1.3.1 What equipment was used

For the current study, a Canon PowerShot G15 camera with 12.1 MegaPixels and

visible, UV, and IR capabilities was used to record the images. The camera is sensitive from

340 nm to 1100 nm, and the camera lens has a focal length of 6.1 mm to 30.5 mm, a digital

zoom of 4.0x, and a focusing range of 1 cm to infinity when using different settings. It has a

maximum aperture of f/1.8 and shutter speed of 1-1/4000 seconds.

Two filters were used: a X-Nite Color Correction Filter #1 in 58mm Diameter x 2.2mm

thick, and a X-Nite 850nm Filter in 58mm Diameter x 2.2mm Thick.

A Canon PowerShot G15 58mm Adapter Ring was used to attach the X-Nite 850nm

Filter to the camera as the Canon PowerShot G15 camera has a retractable lens.

A Metz 44 AF-1 mecablitz digital flash for Canon Camera was attached to the top of

the camera using the hotshoe on the Canon PowerShot G15.

An Infrared Down-Conversion Storage Detector Card with absorption from 450 nm to

630 nm, and emission peak from 880 nm to 1055 nm was used as a control.

Duracell rechargeable batteries were used to power the flash, and a SanDisk 32GB

45MB/s Extreme HD Video SDHC Card was used to store the data.

Lastly, a brass retaining ring was built by the workshop at the Stephenson Laboratory at

Cranfield to attach the X-Nite Color Correction Filter to the Metz 44 AF-1 mecablitz digital

flash; the brass frame used small screws and silver soldering to clamp around both the flash

and the filter.

1.3.2 Why the equipment was chosen

The equipment listed above was purchased and used in this experiment in accordance

with Verri (2009a and 2009b), and the recommendations by G. Chiari and M. Svobada at the

Getty Institute.

The PowerShot G15 camera was bought and modified at MaxMax. The camera was

opened, and the inbuilt IR cut filter was removed and replaced with a 715 nm IR filter to

allow IR to be detected by the camera. The anti-aliasing filter was also removed to enable the

camera to take sharper pictures with increased resolution. Lastly, the auto focus function was

modified so that the camera would focus correctly in the IR band. These were necessary

modifications to ensure sharp images could be produced of IR radiation and luminescence.

!


The X-Nite Color Correction Filter was mounted on the flash to block IR radiation

from the flash hitting the sample, and the X-Nite 850nm Filter was mounted on the camera

lens as a cut-off filter to stop IR under 850 nm from being detected by the camera. This limits

the IR sensitivity range from 850 nm to 1,100 nm. The X-Nite 850nm Filter will let in some

visible light when using the camera under fluorescent lights with no source of IR, causing the

whole image to appear slightly luminescent. This set up can be seen in Figure 3.

Figure 3: Schematic representation of the way in which the system of camera and filters works.

The detector card was used as a control for the ambient radiation in the room to allow

the luminescence from the samples to be better analysed.

1.4 Aims and objectives

The aim of this project was to construct, finesse, and test on museum artefacts, a

camera that can detect the presence of Egyptian Blue pigment.

The objectives were to set up and run control tests by 20 May, to test the different flash

exposures and see what effect they had by 23 May, to test the difference between taking

pictures in the light and the dark by 29 May, to test the camera on other minerals by 31 May,

and to test the camera on artefacts at the Ashmolean Museum by 21 June.

!"#$%

&#'()#

*)+,-./0123+41-567+768.96:

*247;76:+7;:1;51.2+,-./06:

)64-6/56:+<57;=+*)+7;:1;51.2;2:+->8126</62/6

?@AB'+!*"C()

$#'D"(

&E"E)+&E))(&C*EB+!*"C()

!


Chapter 2: METHODOLOGY

2.1 Camera set up

To secure the X-Nite 850nm Filter to the Canon PowerShot G15 camera, the Canon

PowerShot G15 58mm Adapter Ring was threaded onto the camera. This ring kept the filter

in place in front of the retractable lens of the camera so that when the camera was used and

the lens extended forward, the filter would not be hit, and would remain in front of the lens.

The Metz 44 AF-1 mecablitz digital flash was fitted with the brass retaining ring so that

the X-Nite Color Correction Filter was firmly attached to the flash; the retaining ring allowed

the filter to completely cover the flash regardless of the different shapes of the filter and the

flash.

The flash was mounted on the camera using the hotshoe on top of the camera which

allowed the matching adapter on the bottom of the flash to be inserted and screwed securely

into place.

The set up can be seen in Figures 4-6.

Figure 4: Front view of flash and camera.

!


Figure 5: Side view of flash and camera.

Figure 6: Back view of flash and camera.

!

2.2 Control set up

2.2.1 Conditions of control

Control tests were run to experiment against later using a sample of four small pieces of

Egyptian blue pigment mounted in resin (made and mounted by a previous MSc student of

Dr. Andrew Shortland); the following conditions were observed.

The control tests were run in the dark room at the Rutherford Laboratory at Cranfield

University. The sample of Egyptian blue was placed on a counter with the detection card

below it, as can be seen in Figures 7 and 8.

!


Figure 7: Laboratory set up overview.

Figure 8: Sample and infrared detection card set up.

Per instructions from the Getty Institute, the camera was set on the ‘P’ (program)

setting on the main dial, with an ISO of 100. This setting ensured that the pictures were not

too grainy and allowed for more detail and a better image quality in the dark settings.

The flash was set for through-the-lens metering; this allowed for measuring light levels

through the camera’s taking lens and for manual control over the average luminance emitted

by the flash which was integral to the tests.

Three focusing range modes were used: ‘normal’ with a shooting distance of 5 cm to

infinity at a widest angle setting, and 40 cm to infinity at the telephoto angle setting; ‘macro’

with a shooting distance of 1 cm to 50 cm; ‘manual focus’ with a shooting distance of 1 cm to

infinity.

!


The camera was held approximately 30 cm away from the control sample of Egyptian

blue, level to the counter the sample rested on.

2.2.2 How results are read

When using the ‘normal’ focusing range, the recorded images appear almost

completely pink, with black around the edges. The Egyptian blue appears a very bright,

almost white, pink.

When using the ‘macro’ focusing range, the recorded images appear completely black,

except for the Egyptian blue which appears a bright pink.

When using the ‘manual focus’ focusing range, the recorded images appear lightly

pink, with the Egyptian blue appearing a bright pink.

With all settings, the infrared down-conversion storage detector card can be seen in the

recorded images and appears a duller pink than the Egyptian blue, though it can be quite

bright with the ‘normal’ setting. This is used as a control since it has an emission peak from

880 nm to 1055 nm which brackets the 950 nm emission peak of Egyptian blue, so the

detector card was always present in the images to ensure the proper settings were in place to

detect Egyptian blue.

2.3 Dark vs. light test set up !

2.3.1 Conditions of experiment in dark

The set up of the camera, flash, control Egyptian blue sample, and detector card

remained the same as the control tests. The images were recorded in the pitch black of the

dark room: no light was present at all.

Two focusing range modes were used as initial test groups: normal and macro. Each

positive flash exposure setting from 0 to +3 was tested ten times to avoid errors; this was

repeated with both focusing ranges.

After initial testing, the best settings were chosen for clarity of the luminescence of

Egyptian blue, and the manual focus focusing range was used at this setting to provide the

most defined image of the sample.

!


2.3.2 Conditions of experiment in light


remained the same as the control tests. The images were recorded in the dark room with a

single Fitzgerald Lighting 65/80-watt fluorescent bulb on; it was mounted on the ceiling of

the dark room over the sample, and no other light was able to enter the room.

Two focusing range modes were used as initial test groups: normal and macro. Each

positive flash exposure setting from 0 to +3 was tested ten times to avoid errors; this was

repeated with both focusing ranges.

After initial testing, the best settings were chosen for clarity of the luminescence of

Egyptian blue, and the manual focus focusing range was used at this setting to provide the

most defined image of the sample.

2.3.3 Conditions of experiment in indirect sunlight


remained the same as the control tests. The images were recorded in the shade of a building

directly in the path of the sunlight on a cloudless day at 11.00 am at 51.60331 degrees

latitude and -1.642333 degrees longitude.

Each flash exposure setting from -3 to +3 was tested twice to avoid errors; the camera

was set to 17 cm magnification and a manual focus focusing range of 18 cm was used.

2.3.4 Conditions of experiment in direct sunlight


remained the same as the control tests. The images were recorded in direct sunlight on a

cloudless day at 10.30 am at 51.603353 degrees latitude and -1.642341 degrees longitude.

Each flash exposure setting from -3 to +3 was tested twice to avoid errors; the camera

was set to 18 cm magnification and a manual focus focusing range of 18 cm was used.

2.4 Other minerals test set up

2.4.1 List of minerals that were tested Phyllite: Loch Leven, West Scotland

Rhyolite: Scotland

Granodiorite: beside the loch at Strontian, Scotland

!


Andesite: Gatesgarth, Buttermere, Cumbria

Diorite-Quartz: lower Glen Coe, Scotland

Diorite: Cockermouth, Cumbria

Quartzite and malachite and cuproadant: Cap Garonne, Var, France

Quartzite: Holy Island, Anglesey

Pegmatite (pink feldspar/quartz): Evje area, South Norway

Alnoite: Alno island, Baltic coast, Sweden

Porphyry: Alvadalen, Mora, Sweden

Porphyry (Quartz-Porphyry): Armboth Dyke Thirlwere, Cumbria

Porphyry (Quartz-Porphyry): Gwennap, Cornwall

Slate with Chiastolite: Glenderaterra near Skiddaw, Cumbria

Aplite: near Scirignac, Brittany, France

Pegmatite (Zircon in Quartz and Feldspar): Ontario, Canada

Porphyry, France

Porphyry, Canisp, Scotland

Pitchstone: Arran, Scotland

Gneiss Stronian, Argyllshire, Scotland

Mudstone: Kimmeridge, Dorset, England

Shale: Kimmeridge, Dorset, England

Agglomerate: Glen Coe, Scotland

Obsidian: USA

Gneiss (black and white): Scotland

Slate: Delabole Quarry, near Tintagel, North Cornwall

Siltstone: Moughton Whetstone, near Austwick, Yorkshire

Breccia: Brockram, Cumbria

Granite Strontian: Argylshire, Scotland

Granite Shap: Cumbria

Granite (Pink Granite)

Granite Merrivale: Dartmoor, Devon

Granite: Rapakivi, Finland

Granite: Redhills, Skye, Scotland

Granite: Le’Etacq Quarry, Jersey, Channel Islands

Granite Pophyry with pink feldspars: Camborne, Cornwall

Granite: Eepoo, Finland

!


Granite Pegmatite: Durness, Sutherland, Scotland

Phyllite: Belmont Unst, Shetlands

Basalt: Skye, Scotland

Basalt: near Sanquahar, Ayrshire, Scotland

Basalt: Sconser, Skye, Scotland

Gabbro: Dalgellau, Wales

Quartzite: Ightham, near Sevenoaks, Kent

Agglomerate: Cwrm Llan, Snowdoria, Wales

Dolerite: Derbyshire

Gabbro: Caldbeck Fells, Cumbria

Gabbro: Porthoustock, Lizard, Cornwall

Sandstone: Achnahaird Bay, North/West Scotland

Sandstone: near St David’s, Pembrokeshire, Wales

Sandstone: Surrey

Sandstone: Femgirous, Hurtanter, Norfolk

Sandstone: Miscaeus, Yorkshire

Sandstone: near Penrite, Cumbria

Sandstone: Godalmina, Surrey

Sandstone with Glauconite: Cow Gap, Eastbourne, Sussex

Sandstone, Cumbria

Limestone (Shelly limestone)

Limestone: Headon beds, near Freshwater, I.O.W.

Limestone, Derbyshire

Limestone (Crinoidal limestone): Derbyshire

Chaulk: near Effingham, Surrey

Marble: Skye, Scotland

Marble: Carrara, Apuan area, Italy

Eclogite, Nordfjord, Norway

Hornfels: near Carrock Mine, from Skiddaw area, Cumbria

Schist: Scotland

Schist: Arnes, near Oslo, Norway

Schist (Garnet Schist): Glen Roy, West Scotland

Fine-grain Biotite Schist and Garnets: Sweden

Schist and Horblende: Kopparberg, Sweden

!


Tuff: near Church Stretton, Shroshire

Tuff: Sheddesdale, Cumbria

Tuff (“Green Slate”): Borrowdale, Cumbria

Ignimbrite: Dingle Peninsula, South Ireland

Pumice: Italy

Tephrite with Leucite, Taualota, Rome

Tuff (“Birds Eye”): Long Sleddodale, Cumbria

Trachyte: Puy de la Tache, Mont Dere, Puy de Dome, France

2.4.2 Conditions of tests

The set up of the camera, flash, and detector card remained the same as the control

tests. The control conditions of the dark and light tests were observed.

The camera was set to 11 cm magnification, with a manual focus focusing range of 18

cm, and the flash was set to a +2 1/3 exposure.

Two photos were taken each in the dark and in the light of each mineral, as well as a

‘normal’ photo taken without the use of filters to provide a comparison image to the Egyptian

blue luminescent images.

2.5 Ashmolean Museum materials test set up !

2.5.1 List of materials that were tested In order of oldest to newest object:

AN1885.504: limestone false door from the tomb of the Overseer of Officials, Weri; Giza,

Old Kingdom, 6th Dynasty.

AN1954.25: limestone stele with traces of paint, depicting Dedusobek and his mother, Senet,

standing at a table of offerings, unprovenanced, Middle Kingdom, 12th dynasty.

QCL113: painted limestone stele of Ankhreni, steward of the granary, with his brother and

sister-in-law; the inscription exhorts people to recite the offering prayer; Abydos; Middle

Kingdom.

!


AN1889.1030, 1032: painted limestone relief sculpture from the tomb of Intefiker, who is

shown below an inscription recording his name and titles; Lahun, Middle Kingdom, 12th

Dynasty.

AN1893.1-41(167): fragment of sandstone doorjamb inscribed with the cartouche of King

Akhenaten; Tell el-Amarna, New Kingdom, 18th Dynasty.

AN1893.1-41(114): limestone architectural fragments from Akhetaten inscribed with the

cartouches of Akhetaten and Nefertiti facing those of the Aten; New Kingdom, 18th Dynasty.

Blue painted pottery fragments: Tell el-Amarna, 18th-20th Dynasties.

AN1894.107A: limestone stele recording a series of oracles delivered by the god Seth to

settle a land dispute; Mut, Dakhla Oasis, 22nd Dynasty.

AN1936.662: sandstone wall depicting King Aspelta offering Ma’at to Amun-Re, who is

accompanied by the goddess Anukis; the doorway gave access to a small chamber between

the Shrine of Taharqa and the main temple wall; Temple T at Kawa, Napatan Period (593-

568 BCE), 25th Dynasty.

AN1936.661: Shrine of Taharqa: Kingdom of Kush, 25th Dynasty. The west wall shows King

Taharqa before the gods of Germaten (the temple at Kawa). He offers a loaf, a pectoral, and a

figure of Ma’at to the ram-headed god Amun-Re. Behind the god’s throne are the goddesses

Anukis Nethy, Satis, and Anukis Ba. The east wall shows King Tahaqra and the gods of

Thebes. He offers a white loaf to Amun-Re, accompanied by Mut, Khonshu, and Montu. The

north wall illustrates King Taharqa standing before Sekhmet and Nefertum-Horakhty, the

other two gods of the Memphite triad.

AN1971.994: stone relief showing captives and loot from a Babylonian city during a raid by

Sennacherib, below is a river with fish; sixth-seventh century BCE.

ANLOAN109.1: partial inscription from an Akkadian cuneiform documenting

Ashurnasirpal’s achievements and expressed loyalty to the gods; ninth century BCE.

!


Michaelis.77, Michaelis.4: marble statue of a woman; the hairstyle dates the head to the later

Roman Republic or Augustan period, whereas the body was much earlier; head: Roman, 20

BCE-20 CE; body: 200-100 BCE.

Michaelis.43: painted marble statue of a young man; Hellenistic Greek, Western Turkey or

the Aegean Islands; 150-50 BCE.

Michaelis.111: front panel from a sarcophagus lid showing three scenes from the Trojan War,

framed by heads wearing Phyrygian caps; Roman; 175-225 CE.

Michaelis.225: marble pilaster; probably once part of the richly decorated façade of a Roman

building from Western Turkey; the relief decoration shows a candelabrum with an ornate

altar, palm tree and small cup above the top branches; Roman; 175-225 CE.

Michaelis.32: marble statue of Clio, the muse of history; Roman; 1-200 CE.

Michaelis.31: seated marble statute, likely Terpsichore, the muse of dance; Roman; 50-150

CE.

AN1947.270: statue of a priestess from the port of Antium, Italy; Roman 120-150 CE.

AN1888.340: mummy portrait painted in encaustic showing a bearded man wearing a white

robe with a red band over the shoulder, second century CE, no provenance.

AN1888.341: mummy portrait fragment painted in tempera showing part of the head of a

bearded man with curly hair, second century CE, no provenance.

AN1888.342: mummy portrait fragment painted in encaustic showing a man with curly hair

wearing a white robe with a red band on the shoulder, and a gilt wreath with a gilt streamer

hanging over his shoulder, second century CE, no provenance.

AN1888.1178: mummy portrait painted in encaustic showing the head of a young man

wearing a gilded wreath, and a white robe with a red band hanging from a fold on the

shoulder, second century CE, Fayum, Egypt.

!


AN1890.756 (=AN1963.2): mummy portrait with the right half missing painted in tempera

showing a bearded man wearing a white robe with a red band on the shoulder and gilt wreath,

second century CE, er-Rubaiyat, Egypt.

AN1966.1112: double-sided mummy portrait painted in encaustic showing a young woman

with short curly hair wearing a light brown dress with red shoulder draperies, a necklace with

a gold, crescent-shaped pendant, and gold hoop earrings, second century CE, Fayum, Egypt.

2.5.2 Conditions of tests

The mummy portraits were tested in the Conservation Studios at the Ashmolean

Museum since they were not on display in the museum, like the other artefacts tested. The set

up of the camera and flash remained the same as the control tests, but instead of being held

approximately 30 cm from the test surface, the camera was mounted on a frame built

specifically for taking pictures of artefacts in the Conservation Studios. The frame included a

tripod thumbscrew that could be mated into the female receptacle of the camera, securing the

camera firmly into place, at a 90° angle to the test surface; see Figures 9 and 10. This ensured

that the camera would be at an exact angle and distance from the objects tested.!

!

!Figure 9: Side view of the Ashmolean frame with the camera mounted on it.!

!


!Figure 10: Front view of the Ashmolean frame with the camera mounted on it.!

When testing in the Conservation Studios, the dark conditions were not completely

dark as no dark room was available, and the door to the room used had a small window in it.

However, all lights were turned off and the room was as dark as possible in that environment.

The manual focus focusing range was used and changed depending on the desired

magnification of the mummy portrait and a flash exposure setting of +2 1/3 was used.

However, the majority of objects tested at the Ashmolean were on display, and were

therefore unable to be moved; this prevented accurate test conditions as the lights could not

be controlled in any way. The lights at the museum are overhead LED lights.

The set up of the camera, flash, and detector card remained the same as the control

tests. The manual focus focusing range was used and changed depending on how far the

object was away from the camera, and the flash was set to a +2 1/3 exposure.

A ‘normal’ photo was taken of each object without the use of filters to provide a

comparison image to the Egyptian blue luminescent images. Two photos of each object were

taken using the Egyptian blue filters at each magnification tested; the time constraints on this

testing phase did not permit further testing which would have been preferable.

!


Chapter 3: RESULTS

3.1 Light vs. dark test results One of each of the multiple images recorded at each flash exposure setting was chosen to best

represent the full set of images.

3.1.1 Dark results

Figure 11: Egyptian blue sample: dark; macro

focusing range; flash exposure: 0.

Figure 12: Egyptian blue sample: dark; normal

focusing range; flash exposure: +1/3.




focusing range; flash exposure: +1.

!



focusing range; flash exposure: +1 1/3.











!














!





focusing range; flash exposure: + 2 1/3.



!



Figure 31: Egyptian blue sample: dark; manual focus focusing range (18); flash exposure +2 1/3.

!!!!!

!


3.1.2 Light results

Figure 32: Egyptian blue sample: light; macro












!










Figure 42: Egyptian blue sample: light; normal




!














!






Figure 52: Egyptian blue sample: light, manual focus focusing range (18); flash exposure: +2 1/3.

!

3.1.3 Indirect sunlight results

Figure 53: Egyptian blue sample: indirect

sunlight; manual focus focusing range (18); flash exposure: -3.


sunlight; manual focus focusing range (18); flash exposure: -2 2/3.

!













sunlight; manual focus focusing range (18); flash exposure: -2/3.

!



sunlight; manual focus focusing range (18); flash exposure: -1/3.


sunlight; manual focus focusing range (18); flash exposure: 0.


sunlight; manual focus focusing range (18); flash exposure: +1/3.


sunlight; manual focus focusing range (18); flash exposure: +2/3.


sunlight; manual focus focusing range (18); flash exposure: +1.


sunlight; manual focus focusing range (18); flash exposure: +1 1/3.

!






!



!!





!


3.1.4 Direct sunlight results

Figure 72: Egyptian blue sample: direct sunlight;

manual focus focusing range (18); flash exposure: -3.


manual focus focusing range (18); flash exposure: -2 2/3.









!





manual focus focusing range (18); flash exposure: -2/3.


manual focus focusing range (18); flash exposure: -1/3.


manual focus focusing range (18); flash exposure: 0.


manual focus focusing range (18); flash exposure: +1/3.


manual focus focusing range (18); flash exposure: +2/3.

!



manual focus focusing range (18); flash exposure: +1.


manual focus focusing range (18); flash exposure: +1 1/3.









!




3.3 Other minerals results

Figure 91: Phyllite: Loch

Leven, West Scotland: normal; manual focus focusing range (20); flash exposure: +2 1/3.


Leven, West Scotland: light; manual focus focusing range (20); flash exposure: +2 1/3.


Leven, West Scotland: dark; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 94: Rhyolite: Scotland: normal; manual focus focusing range (20); flash exposure: +2

1/3.

Figure 95: Rhyolite: Scotland: light; manual focus focusing

range (20); flash exposure: +2 1/3

Figure 96: Rhyolite: Scotland: dark; manual focus focusing

range (20); flash exposure: +2 1/3.

!


Figure 97: Granodiorite: beside the loch at Strontian, Scotland: normal; manual focus focusing range (20); flash exposure: +2

1/3.

Figure 98: Granodiorite: beside the loch at Strontian, Scotland: light; manual focus focusing


Figure 99: Granodiorite: beside the loch at Strontian, Scotland:

dark; manual focus focusing range (20); flash exposure: +2

1/3.

Figure 100: Andesite:

Gatesgarth, Buttermere, Cumbria: normal; manual focus

focusing range (20); flash exposure: +2 1/3.


Gatesgarth, Buttermere, Cumbria: light; manual focus

focusing range (20); flash exposure: +2 1/3


Gatesgarth, Buttermere, Cumbria: dark; manual focus


Figure 103: Diorite-Quartz: lower Glen Coe, Scotland:

normal; manual focus focusing range (20); flash exposure: +2

1/3


light; manual focus focusing range (20); flash exposure: +2

1/3



1/3.

!


Figure 106: Diorite: Cockermouth, Cumbria:


1/3.

Figure 107: Diorite: Cockermouth, Cumbria: light; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 108: Diorite:

Cockermouth, Cumbria: dark; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 109: Quartzite and malachite and cuproadant: Cap Garonne, Var, France: normal; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 110: Quartzite and malachite and cuproadant: Cap

Garonne, Var, France: light; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 111: Quartzite and

malachite and cuproadant: Cap Garonne, Var, France: dark; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 112: Quartzite: Holy Island, Anglesey: normal;


Figure 113: Quartzite: Holy Island, Anglesey: light; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 114: Quartzite: Holy

Island, Anglesey: dark; manual focus focusing range (20); flash

exposure: +2 1/3.

!


Figure 115: Pegmatite (pink feldspar/quartz): Evje area,

South Norway: normal; manual focus focusing range (20); flash

exposure: +2 1/3.


South Norway: light; manual focus focusing range (20); flash

exposure: +2 1/3.


South Norway: dark; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 118: Alnoite: Alno island, Baltic coast, Sweden:


1/3.

Figure 119: Alnoite: Alno island, Baltic coast, Sweden: light; manual focus focusing


Figure 120: Alnoite: Alno

island, Baltic coast, Sweden: dark; manual focus focusing


Figure 121: Porphyry: Alvadalen, Mora, Sweden:


1/3.

Figure 122: Porphyry: Alvadalen, Mora, Sweden:


1/3.

Figure 123: Porphyry:

Alvadalen, Mora, Sweden: dark; manual focus focusing


!


Figure 124: Porphyry (Quartz-Porphyry): Armboth Dyke

Thirlwere, Cumbria: normal; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 125: Porphyry (Quartz-Porphyry): Armboth Dyke Thirlwere, Cumbria: light;


Figure 126: Porphyry (Quartz-

Porphyry): Armboth Dyke Thirlwere, Cumbria: dark;


Figure 127: Porphyry (Quartz-Porphyry): Gwennap,

Cornwall: normal; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 128: Porphyry (Quartz-Porphyry): Gwennap,

Cornwall: light; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 129: Porphyry (Quartz-

Porphyry): Gwennap, Cornwall: dark; manual focus


Figure 130: Slate with Chiastolite: Glenderaterra near

Skiddaw, Cumbria: normal; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 131: Slate with Chiastolite: Glenderaterra near

Skiddaw, Cumbria: light; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 132: Slate with

Chiastolite: Glenderaterra near Skiddaw, Cumbria: dark;


!


Figure 133: Aplite: near Scirignac, Brittany, France:


1/3.

Figure 134: Aplite: near Scirignac, Brittany, France: light; manual focus focusing


Figure 135: Aplite: near

Scirignac, Brittany, France: dark; manual focus focusing


Figure 136: Pegmatite (Zircon in Quartz and Feldspar): Ontario, Canada: normal;


Figure 137: Pegmatite (Zircon in Quartz and Feldspar):

Ontario, Canada: light; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 138: Pegmatite (Zircon

in Quartz and Feldspar): Ontario, Canada: dark; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 139: Porphyry, France: normal; manual focus focusing range (20); flash exposure: +2

1/3.

Figure 140: Porphyry, France: light; manual focus focusing


Figure 141: Porphyry, France: dark; manual focus focusing


!


Figure 142: Porphyry, Canisp, Scotland: normal; manual focus


Figure 143: Porphyry, Canisp, Scotland: light; manual focus


Figure 144: Porphyry, Canisp, Scotland: dark; manual focus


Figure 145: Pitchstone: Arran, Scotland: normal; manual focus


Figure 146: Pitchstone: Arran, Scotland: light; manual focus


Figure 147: Pitchstone: Arran, Scotland: dark; manual focus


Figure 148: Gneiss Stronian, Argyllshire, Scotland: normal; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 149: Gneiss Stronian, Argyllshire, Scotland: light; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 150: Gneiss Stronian, Argyllshire, Scotland: dark; manual focus focusing range (20); flash exposure: +2 1/3.

!


Figure 151: Mudstone: Kimmeridge, Dorset, England: normal; manual focus focusing range (20); flash exposure: +2

1/3.

Figure 152: Mudstone: Kimmeridge, Dorset, England: light; manual focus focusing


Figure 153: Mudstone:

Kimmeridge, Dorset, England: dark; manual focus focusing


Figure 154: Shale: Kimmeridge, Dorset, England: normal; manual focus focusing range (20); flash exposure: +2

1/3.

Figure 155: Shale: Kimmeridge, Dorset, England: light; manual focus focusing


Figure 156: Shale:

Kimmeridge, Dorset, England: dark; manual focus focusing


Figure 157: Agglomerate: Glen Coe, Scotland: normal; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 158: Agglomerate: Glen Coe, Scotland: light;


Figure 159: Agglomerate: Glen

Coe, Scotland: dark; manual focus focusing range (20); flash

exposure: +2 1/3.

!


Figure 160: Obsidian: USA: normal; manual focus focusing range (20); flash exposure: +2

1/3.

Figure 161: Obsidian: USA: light; manual focus focusing


Figure 162: Obsidian: USA: dark; manual focus focusing


Figure 163: Gneiss (black and white): Scotland: normal;


Figure 164: Gneiss (black and white): Scotland: light; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 165: Gneiss (black and white): Scotland: dark; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 166: Slate: Delabole Quarry, near Tintagel, North Cornwall: normal; manual

focus focusing range (20); flash exposure: +2 1/3.

Figure 167: Slate: Delabole Quarry, near Tintagel, North


exposure: +2 1/3.

Figure 168: Slate: Delabole Quarry, near Tintagel, North Cornwall: dark; manual focus


!


Figure 169: Siltstone: Moughton Whetstone, near

Austwick, Yorkshire: normal; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 170: Siltstone: Moughton Whetstone, near Austwick, Yorkshire: light;


Figure 171: Siltstone:

Moughton Whetstone, near Austwick, Yorkshire: dark;


Figure 172: Breccia: Brockram, Cumbria: normal; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 173: Breccia: Brockram, Cumbria: light;


Figure 174: Breccia: Brockram,

Cumbria: dark; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 175: Granite Strontian: Argylshire, Scotland: normal; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 176: Granite Strontian: Argylshire, Scotland: light;


Figure 177: Granite Strontian:

Argylshire, Scotland: dark; manual focus focusing range (20); flash exposure: +2 1/3.

!


Figure 178: Granite Shap: Cumbria: normal; manual focus


Figure 179: Granite Shap: Cumbria: light; manual focus


Figure 180: Granite Shap:


exposure: +2 1/3.

Figure 181: Granite (Pink Granite): normal; manual focus


Figure 182: Granite (Pink Granite): light; manual focus


Figure 183: Granite (Pink

Granite): dark; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 184: Granite Merrivale: Dartmoor, Devon: normal;


Figure 185: Granite Merrivale: Dartmoor, Devon: light;


Figure 186: Granite Merrivale:

Dartmoor, Devon: dark; manual focus focusing range (20); flash exposure: +2 1/3.

!


Figure 187: Granite: Rapakivi, Finland: normal; manual focus


Figure 188: Granite: Rapakivi, Finland: light; manual focus


Figure 189: Granite: Rapakivi,

Finland: dark; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 190: Granite: Redhills, Skye, Scotland: normal;


Figure 191: Granite: Redhills, Skye, Scotland: light; manual


Figure 192: Granite: Redhills, Skye, Scotland: dark; manual


Figure 193: Granite: Le’Etacq Quarry, Jersey, Channel

Islands: normal; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 194: Granite: Le’Etacq Quarry, Jersey, Channel

Islands: light; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 195: Granite: Le’Etacq

Quarry, Jersey, Channel Islands: dark; manual focus focusing range (20); flash

exposure: +2 1/3.

!


Figure 196: Granite Pophyry with pink feldspars: Camborne,


exposure: +2 1/3.

Figure 197: Granite Pophyry with pink feldspars: Camborne, Cornwall: light; manual focus


Figure 198: Granite Pophyry

with pink feldspars: Camborne, Cornwall: dark; manual focus


Figure 199: Granite: Eepoo, Finland: normal; manual focus


Figure 200: Granite: Eepoo, Finland: light; manual focus


Figure 201: Granite: Eepoo, Finland: dark; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 202: Granite Pegmatite: Durness, Sutherland, Scotland: normal; manual focus focusing range (20); flash exposure: +2

1/3.

Figure 203: Granite Pegmatite: Durness, Sutherland, Scotland: light; manual focus focusing


Figure 204: Granite Pegmatite: Durness, Sutherland, Scotland:


1/3.

!


Figure 205: Phyllite: Belmont Unst, Shetlands: normal;


Figure 206: Phyllite: Belmont Unst, Shetlands: light; manual


Figure 207: Phyllite: Belmont Unst, Shetlands: dark; manual


Figure 208: Basalt: Skye, Scotland: normal; manual focus focusing range (20);

flash exposure: +2 1/3.

Figure 209: Basalt: Skye, Scotland: light; manual


Figure 210: Basalt: Skye, Scotland: dark; manual


Figure 211: Basalt: near Sanquahar, Ayrshire, Scotland: normal; manual focus focusing range (20); flash exposure: +2

1/3.

Figure 212: Basalt: near Sanquahar, Ayrshire, Scotland:


1/3.

Figure 213: Basalt: near

Sanquahar, Ayrshire, Scotland: dark; manual focus focusing


!


Figure 214: Basalt: Sconser, Skye, Scotland: normal;


Figure 215: Basalt: Sconser, Skye, Scotland: light; manual


Figure 216: Basalt: Sconser, Skye, Scotland: dark; manual


Figure 217: Gabbro: Dalgellau, Wales: normal; manual focus


Figure 218: Gabbro: Dalgellau, Wales: light; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 219: Gabbro: Dalgellau,

Wales: dark; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 220: Quartzite: Ightham, near Sevenoaks, Kent: normal; manual focus focusing range (20); flash exposure: +2

1/3.

Figure 221: Quartzite: Ightham, near Sevenoaks, Kent:


1/3.

Figure 222: Quartzite: Ightham,

near Sevenoaks, Kent: dark; manual focus focusing range (20); flash exposure: +2 1/3.

!


Figure 223: Agglomerate: Cwrm Llan, Snowdoria, Wales: normal; manual focus focusing range (20); flash exposure: +2

1/3.

Figure 224: Agglomerate: Cwrm Llan, Snowdoria, Wales:


1/3.

Figure 225: Agglomerate:

Cwrm Llan, Snowdoria, Wales: dark; manual focus focusing


Figure 226: Dolerite: Derbyshire: normal; manual


Figure 227: Dolerite: Derbyshire: light; manual focus


Figure 228: Dolerite:

Derbyshire: dark; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 229: Gabbro: Caldbeck Fells, Cumbria: normal; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 230: Gabbro: Caldbeck Fells, Cumbria: light; manual


Figure 231: Gabbro: Caldbeck Fells, Cumbria: dark; manual


!


Figure 232: Gabbro: Porthoustock, Lizard,


exposure: +2 1/3.



exposure: +2 1/3.


Cornwall: dark; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 235: Sandstone: Achnahaird Bay, North/West

Scotland: normal; manual focus focusing range (20); flash

exposure: +2 1/3 .

Figure 236: Sandstone: Achnahaird Bay, North/West Scotland : light; manual focus


Figure 237: Sandstone:

Achnahaird Bay, North/West Scotland: dark; manual focus


Figure 238: Sandstone: near St David’s, Pembrokeshire,

Wales: normal; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 239: Sandstone: near St David’s, Pembrokeshire,

Wales: light; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 240: Sandstone: near St

David’s, Pembrokeshire, Wales: dark; manual focus focusing range (20); flash

exposure: +2 1/3.

!


Figure 241: Sandstone: Surrey: normal; manual focus focusing range (20); flash exposure: +2

1/3.

Figure 242: Sandstone: Surrey: light; manual focus focusing


Figure 243: Sandstone: Surrey:


1/3.

Figure 244: Sandstone: Femgirous, Hurtanter, Norfolk: normal; manual focus focusing range (20); flash exposure: +2

1/3

Figure 245: Sandstone: Femgirous, Hurtanter, Norfolk:


1/3.


Femgirous, Hurtanter, Norfolk: dark; manual focus focusing


Figure 247: Sandstone: Miscaeus, Yorkshire: normal; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 248: Sandstone: Miscaeus, Yorkshire: light;



Miscaeus, Yorkshire: dark; manual focus focusing range (20); flash exposure: +2 1/3.

!


Figure 250: Sandstone: near Penrite, Cumbria: normal;


Figure 251: Sandstone: near Penrite, Cumbria: light; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 252: Sandstone: near

Penrite, Cumbria: dark; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 253: Sandstone: Godalmina, Surrey: normal; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 254: Sandstone: Godalmina, Surrey: light;



Godalmina, Surrey: dark; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 256: Sandstone with Glauconite: Cow Gap,

Eastbourne, Sussex: normal; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 257: Sandstone with Glauconite: Cow Gap,

Eastbourne, Sussex: light; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 258: Sandstone with

Glauconite: Cow Gap, Eastbourne, Sussex: dark;


!


Figure 259: Sandstone, Cumbria: normal; manual focus


Figure 260: Sandstone, Cumbria: light; manual focus


Figure 261: Sandstone,


exposure: +2 1/3.

Figure 262: Limestone (Shelly limestone): normal; manual


Figure 263: Limestone (Shelly limestone): light; manual focus


Figure 264: Limestone (Shelly limestone): dark; manual focus


Figure 265: Limestone: Headon beds, near Freshwater, I.O.W.: normal; manual focus


Figure 266: Limestone: Headon beds, near Freshwater,

I.O.W.: light; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 267: Limestone: Headon beds, near Freshwater, I.O.W.: dark; manual focus focusing


!


Figure 268: Limestone, Derbyshire: normal; manual


Figure 269: Limestone, Derbyshire: light; manual focus


Figure 270: Limestone,


exposure: +2 1/3

.

Figure 271: Limestone (Crinoidal limestone):

Derbyshire: normal; manual focus focusing range (20); flash

exposure: +2 1/3.


Derbyshire: light; manual focus focusing range (20); flash

exposure: +2 1/3.



exposure: +2 1/3.

Figure 274: Chaulk: near Effingham, Surrey: normal; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 275: Chaulk: near Effingham, Surrey: light;


Figure 276: Chaulk: near Effingham, Surrey: dark;


!


Figure 277: Marble: Skye, Scotland: normal; manual focus


Figure 278: Marble: Skye, Scotland: light; manual focus


Figure 279: Marble: Skye,

Scotland: dark; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 280: Marble: Carrara, Apuan area, Italy: normal;


Figure 281: Marble: Carrara, Apuan area, Italy: light; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 282: Marble: Carrara,

Apuan area, Italy: dark; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 283: Eclogite, Nordfjord, Norway: normal; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 284: Eclogite, Nordfjord, Norway: light;


Figure 285: Eclogite,

Nordfjord, Norway: dark; manual focus focusing range (20); flash exposure: +2 1/3.

!


Figure 286: Hornfels: near Carrock Mine, from Skiddaw

area, Cumbria: normal; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 287: Hornfels: near Carrock Mine, from Skiddaw area, Cumbria: light; manual


Figure 288: Hornfels: near

Carrock Mine, from Skiddaw area, Cumbria; normal; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 289: Schist: Scotland: normal; manual focus focusing range (20); flash exposure: +2

1/3.

Figure 290: Schist: Scotland: light; manual focus focusing


Figure 291: Schist: Scotland: dark; manual focus focusing


Figure 292: Schist: Arnes, near Oslo, Norway: normal; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 293: Schist: Arnes, near Oslo, Norway: light; manual


Figure 294: Schist: Arnes, near

Oslo, Norway: dark; manual focus focusing range (20); flash

exposure: +2 1/3.

!


Figure 295: Schist (Garnet Schist): Glen Roy, West

Scotland: normal; manual focus focusing range (20); flash

exposure: +2 1/3.


Scotland: light; manual focus focusing range (20); flash

exposure: +2 1/3.


Scotland: dark; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 298: Fine-grain Biotite Schist and Garnets: Sweden:


1/3.

Figure 299: Fine-grain Biotite Schist and Garnets: Sweden: light; manual focus focusing


Figure 300: Fine-grain Biotite Schist and Garnets: Sweden: dark; manual focus focusing


Figure 301: Schist and Horblende: Kopparberg,

Sweden: normal; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 302: Schist and Horblende: Kopparberg,

Sweden: light; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 303: Schist and

Horblende: Kopparberg, Sweden: dark; manual focus


!


Figure 304: Tuff: near Church Stretton, Shroshire: normal; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 305: Tuff: near Church Stretton, Shroshire: light;


Figure 306: Tuff: near Church

Stretton, Shroshire: dark; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 307: Tuff: Sheddesdale, Cumbria: normal; manual focus


Figure 308: Tuff: Sheddesdale, Cumbria: light; manual focus


Figure 309: Tuff: Sheddesdale, Cumbria: dark; manual focus


Figure 310: Tuff (“Green Slate”): Borrowdale, Cumbria: normal; manual focus focusing range (20); flash exposure: +2

1/3.

Figure 311: Tuff (“Green Slate”): Borrowdale, Cumbria: light; manual focus focusing


Figure 312: Tuff (“Green

Slate”): Borrowdale, Cumbria: dark; manual focus focusing


!


Figure 313: Ignimbrite: Dingle Peninsula, South Ireland:


1/3.

Figure 314: Ignimbrite: Dingle Peninsula, South Ireland: light; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 315: Ignimbrite: Dingle Peninsula, South Ireland: dark; manual focus focusing range (20); flash exposure: +2 1/3.

Figure 316: Pumice: Italy: normal; manual focus focusing range (20); flash exposure: +2

1/3.

Figure 317: Pumice: Italy: light; manual focus focusing


Figure 318: Pumice: Italy:


1/3.

Figure 319: Tephrite with Leucite, Taualota, Rome:


1/3.

Figure 320: Tephrite with Leucite, Taualota, Rome: light;


Figure 321: Tephrite with

Leucite, Taualota, Rome: dark; manual focus focusing range (20); flash exposure: +2 1/3.

!


Figure 322: Tuff (“Birds Eye”): Long Sleddodale,

Cumbria: normal; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 323: Tuff (“Birds Eye”): Long Sleddodale,

Cumbria: light; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 324: Tuff (“Birds Eye”):

Long Sleddodale, Cumbria: dark; manual focus focusing


Figure 325: Trachyte: Puy de la Tache, Mont Dere, Puy de

Dome, France: normal; manual focus focusing range (20); flash

exposure: +2 1/3.

Figure 326: Trachyte: Puy de la Tache, Mont Dere, Puy de Dome, France: light; manual


Figure 327: Trachyte: Puy de la

Tache, Mont Dere, Puy de Dome, France: dark; manual


!

!


3.3 Ashmolean Museum materials results

3.3.1 Egyptian objects: Old Kingdom

Figure 328: AN1885.504: normal; manual focus

focusing range (30); flash exposure +2 1/3.

Figure 329: AN1885.504: with filters; manual

focus focusing range (30); flash exposure +2 1/3.

Figure 330: AN1885.504 (top right corner):

normal; manual focus focusing range (22); flash exposure: +2 1/3.

Figure 331: AN1885.504 (top right corner): with filters; manual focus focusing range (22); flash

exposure: +2 1/3.

!


3.3.4 Egyptian objects: Middle Kingdom



Figure 333: AN1954.25: with filters; manual focus focusing range (30); flash exposure: +2

1/3.

Figure 334: AN1954.25 (upper half): normal;


Figure 335: AN1954.25 (upper half): with filters;

manual focus focusing range (18); flash exposure: +2 1/3

!


Figure 336: QCL113: normal; manual focus focusing range (16); flash exposure: +2 1/3.

Figure 337: QCL113: with filters; manual focus





1/3.




1/3.

!


3.3.3 Egyptian objects: New Kingdom

Figure 342: AN1893.1-41(167): normal; manual


Figure 343: AN1893.1-41(167): with filters;


Figure 344: AN1893.1-41(114): normal; manual focus focusing range (20); flash exposure +2 1/3.


manual focus focusing range (20); flash exposure +2 1/3.

!


Figure 346: AN1893.1-41(114): normal; manual




Figure 348: Blue painted pottery fragments:


Figure 349: Blue painted pottery fragments: with filters; manual focus focusing range (15); flash

exposure: +2 1/3.

!


Figure 350: AN1894.107A: normal; manual


Figure 351: AN1894.107A: with filters; manual


Figure 352: AN1894.107A (upper detail):


Figure 353: AN1894.107A (upper detail): with filters; manual focus focusing range (20); flash

exposure: +2 1/3.





!


Figure 356: AN1936.662 (west wall: Amun-Re): normal; manual focus focusing range (25); flash

exposure: +2 1/3.

Figure 357: AN1936.662 (west wall: Amun-Re): normal; manual focus focusing range (25) flash

exposure: +2 1/3.

3.3.4 Shrine of Taharqa West Wall

Figure 358: AN1936.661 (west wall: Amun-Re’s headdress): normal; manual focus focusing range

(25); flash exposure: +2 1/3.

Figure 359: AN1936.661 (west wall: Amun-Re’s headdress): with filters; manual focus focusing


!


Figure 360: AN1936.661 (west wall: Amun-Re’s

upper body): normal; manual focus focusing range (25); flash exposure: +2 1/3.

Figure 361: AN1936.661 (west wall: Amun-Re’s upper body): with filters; manual focus focusing



arms): normal; manual focus focusing range (25); flash exposure: +2 1/3.

Figure 363: AN1936.661 (west wall: Amun-Re’s arms): with filters; manual focus focusing range

(25); flash exposure: +2 1/3.

Figure 364: AN1936.661 (west wall: Amun-Re’s leg): normal; manual focus focusing range (25);



leg): with filters; manual focus focusing range (25); flash exposure: +2 1/3.

!


Figure 366:AN1936.661 (west wall: Amun-Re’s foot): normal; manual focus focusing range (25);


Figure 367: AN1936.661 (west wall: Amun-Re’s foot): normal; manual focus focusing range (25);


Figure 368: AN1936.661 (west wall: Anukis

Nethy’s upper body and head): normal; manual focus focusing range (25); flash exposure: +2

1/3.

Figure 369: AN1936.661 (west wall: Anukis Nethy’s upper body and head): with filters;


Figure 370: AN1936.661 (west wall: Satis’s upper body and head): normal; manual focus focusing range (25); flash exposure: +2 1/3.

Figure 371: AN1936.661 (west wall: Sati’s upper

body and head): with filters; manual focus focusing range (25); flash exposure: +2 1/3.

!


Figure 372: AN1936.661 (west wall: Anukis Ba’s upper body and head): normal; manual


Figure 373: AN1936.661 (west wall: Anukis Ba’s upper body and head): normal; manual


East Wall

Figure 374: AN1936.661 (east wall: Taharqa’s upper body and head): normal; manual focus focusing range (25); flash exposure: +2 1/3.

Figure 375: AN1936.661 (east wall: Taharqa’s

upper body and head): with filters; manual focus focusing range (25); flash exposure +2 1/3.

Figure 376: AN1936.661 (east wall: Amun-Re’s

upper body and head): normal; manual focus focusing range (25); flash exposure: +2 1/3.

Figure 377: AN1936.661 (east wall: Amun-Re’s upper body and head): with filters; manual focus


!


Figure 378: AN1936.661 (east wall: Mut’s upper body and head): normal; manual focus focusing


Figure 379: AN1936.661 (east wall: Mut’s upper

body and head): with filters; manual focus focusing range (25); flash exposure: +2 1/3.

Figure 380: AN1936.661 (east wall: Konshu’s upper body and head): normal; manual focus focusing range (25); flash exposure: +2 1/3.

Figure 381: AN1936.661 (east wall: Konshu’s

upper body and head): with filters; manual focus focusing range (25); flash exposure: +2 1/3.

Figure 382: AN1936.661 (east wall: Montu’s upper body and head): normal; manual focus focusing range (25); flash exposure: +2 1/3.

Figure 383: AN1936.661 (east wall: Montu’s

upper body and head): with filters; manual focus focusing range (25); flash exposure: +2 1/3.

!


North Wall

Figure 384: AN1936.661 (north wall): normal;


Figure 385: AN1936.661 (north wall): with

filters; manual focus focusing range (50); flash exposure: +2 1/3.

3.3.5 Near East objects




1/3.

!


Figure 388: ANLOAN109.1: normal; manual focus focusing range (50); flash exposure: +2

1/3.

Figure 389: ANLOAN109.1: with filters; manual


3.3.6 Graeco-Roman objects

Figure 390: Michaelis.77, Michaelis.4: normal;


Figure 391: Michaelis.77, Michaelis.4: with

filters; manual focus focusing range (30); flash exposure +2 1/3.

Figure 392: Michaelis.43: normal; manual focus


Figure 393: Michaelis.43: with filters; manual focus focusing range (20); flash exposure: +2

1/3.

!





1/3.




1/3.

!





1/3.



Figure 401:Michaelis.31: with filters; manual focus focusing range (28); flash exposure: +2

1/3.




1/3.

!


3.3.7 Romano-Egyptian Objects !

!!!Figure 404: AN1888.340: normal; manual focus


!Figure 405: AN1888.340: with filters; manual focus focusing range (18); flash exposure: +2

1/3.




1/3.

!





1/3.




1/3.

!


Figure 412: AN1890.756 (=AN1963.2): normal;


Figure 413: AN1890.756 (=AN1963.2): normal;





1/3.

!





1/3. !!

!


Chapter 4: DISCUSSION

4.1 Dark vs light discussion

As can be seen in the results, the different focusing ranges (macro, normal, and manual

focus) change the colour appearance of the overall recorded image and the Egyptian blue

sample, but there is not a vast difference between the clarity of the images between the dark

and light results. The Egyptian blue pigment is clearly defined from the background of the

image equally in the dark and in the light.

The initial tests done show that the best clarity is reached using a flash exposure of +2

1/3, both with the dark, see Figures 18 and 28, and the light, see Figures 39 and 49,

conditions. After determining this, the manual focus focusing range was used to further

define the sample. By comparing the two images, Figures 31 and 52, it can be seen that

quality of the image of the sample are almost identical, proving that it is possible to use this

camera technique just as well in the light as in the dark.

Past studies have only used this technique in completely dark conditions which is very

limiting when one wishes to test objects that cannot be moved to areas where these conditions

can be acquired. This discovery makes the technique much more of a viable option for initial

testing of objects before further testing which may require moving them.

It should be noted that the entirety of each image recorded in the light conditions

appear slightly pink, and not fully black, as can be seen in later tests completed at the

Ashmolean Museum; this is due to the fluorescent lighting in the room which, as noted by

Verri, causes more ambient light to be recorded by the camera which can be useful when one

wishes to see the full image, and not just the areas which emitted luminescence and indicated

the presence of Egyptian blue.

The outside tests were completed in hopes that this technique could be used on objects

in situ either on excavations or at previously discovered sites where the objects are too big to

be transported to an inside testing site. However, as the images show, at every flash setting, it

is impossible to detect a difference in luminescence between the Egyptian blue sample and

the rest of the image. This is expected, since the experiments done by Verri (2009b: 1016)

proved that using UV radiation sources to excite the Egyptian blue provided no IR emission

and only a faint luminescence.

!


4.2 Other minerals discussion

None of the minerals tested emitted any luminescence in the spectral range the camera

was set to detect. This demonstrates that the detectable areas of the minerals tested do not

likely contain any Egyptian blue, Han blue, or Han purple, as those three minerals would be

detected using this system of filters. It is possible that the sides of the minerals untested in the

study contained luminescent properties, but that is unlikely and the minerals were uniform.

The minerals used in this study had not previously been tested in this way; therefore,

although the negative results were expected, it was still a useful test. This test proved not just

that the minerals did not contain any properties which would produce a visible-induced

luminescence detectable by this camera, but that the camera functioned as expected. It would

have been concerning if any of the minerals had emitted luminescence, so it is gratifying that

none of them did so.

4.3 Old Kingdom objects from the Ashmolean Museum discussion

The one example tested from the Old Kingdom period in Egypt is the 6th Dynasty

limestone false door from a tomb in Giza: AN1885.504, seen in Figures 328 to 331. The

entire false door was imaged, but only one small section of the top right corner contained

traces of Egyptian blue. As can be seen in Figure 330 it appears as though there were stripes

of colour painted as decoration at the top of the false door, but only one of these small stripes

appears to have been painted blue, seen in Figure 331. The use of Egyptian blue is not

unheard of during this period: the pigment has been detected in the tomb of Per-Neb’s at Giza

in the 5th Dynasty (Moorey, 1994: 187), and a 5th Dynasty text tells of a king having blue

pigment inscribed in the hieroglyphs on a monument of his (Baines, 1985: 286). However,

the use of Egyptian blue was still quite rare in the Old Kingdom period, and since there is

such a small amount of the pigment on the false door, it is possible this blue was a later

addition.

4.4 Middle Kingdom objects from the Ashmolean Museum discussion

The objects from the Middle Kingdom period in Egypt provided the most clear uses of

the pigment, though most were used in very similar ways. Since it is known that Egyptian

blue was often used in inset writing on stone as it was a thick pigment and easy to press into

indentations in stone (Daniels et al, 2003: 2-3), the results obtained were expected.

!


AN1954.25 is a limestone stele with traces of paint, depicting Dedusobek and his

mother, Senet, standing at a table of offerings, from the 12th dynasty. As expected, Figures

332 to 335 show that Egyptian blue was present only on the upper half of the stele, where the

writing was, and not on the lower half of the stele where the picture was.

QCL113 also clearly shows the use of Egyptian blue in inset hieroglyphs; it is a painted

limestone stele of Ankhreni, steward of the granary, with his brother and sister-in-law from

Abydos during the Middle Kingdom period. In this case, blue pigment was visible in some

parts of the inset hieroglyphs, but not all of them, which can be seen in Figure 336. By using

the camera, it is possible to see the full extent to which Egyptian blue was used on the stele.

However, in this stele, it is possible to see the pigment being used on the picture below the

writing, unlike AN1954.25 which limited the pigment use to the writing. Figure 337 shows a

faint luminescence emitted from the wesekh of all three figures painted, as well as from the

horizontal shelf holding up pots in the middle of the scene. This may imply a development of

the usage of the pigment which likely occurred around this time, as during this period more

examples of varied usages can be seen of the pigment unlike earlier examples where it is

more likely that the pigment could be found in inset hieroglyphs almost exclusively.

Both AN1889.1030 and AN1889.1032 show the use of Egyptian blue on raised

hieroglyphs; they are fragments of a painted limestone relief sculpture from the tomb of

Intefiker, from Lahun in the 12th Dynasty. It can be seen, however, that the pigment appears

to not be used to the same degree as in AN1954.25. To the human eye, there are parts of the

hieroglyphs which appear a dull green-blue colour, seen in Figures 338 and 340, but when

imaged with the camera, it can be seen, in Figures 339 and 341, that the Egyptian blue

present does not appear on these visibly blue sections, but on others, which appear to the

human eye as lacking the presence of visible paint. The results also show that the pigment

was not painted on perfectly, as luminescence can be seen emitted from speckled areas

around the densely painted area; it appears as if either the artist who painted this was not very

talented, or just that Egyptian blue is quite hard to use in small, detailed areas that were not

inset where the pigment could just be pressed into an indent.

Although it was expected to detect Egyptian blue quite abundantly on steles from the

Middle Kingdom period, these tests were very worthwhile as they help provide insight into

the workability and usage of the pigment in this time period, and prove how effective the

camera is. The camera is able to detect the presence of Egyptian blue to the same degree

whether any traces of the pigment remain visible to the human eye or not; the image

produced by the camera shows an even distribution of the pigment within the hieroglyphs,

!


regardless of the visible presence of the pigment, showing that the degree of luminescence

detected by the camera does not rely on the amount of pigment left on the object.

4.5 New Kingdom objects from the Ashmolean Museum discussion

The period of highest use of the pigment was during the New Kingdom period in Egypt

(Berke, 2002: 2483); this period also brought about a richer and more diverse range of

colours being used, including multiple shades of blue (Baines, 1985: 287). Therefore, one

would expect to see a significant increase in the amount of Egyptian blue used and in the

ways it was used.

AN1893.1-41(167) is a fragment of a sandstone doorjamb inscribed with the cartouche

of King Akhenaten from Tell el-Amarna in the 18th Dynasty. As can be seen in Figure 343,

Egyptian blue appears to be present in small amounts spread throughout the inset

hieroglyphs. However, the pigment does not appear to be present in the same way as the

examples from the Middle Kingdom showed: the hieroglyphs are not consistently highlighted

with blue. This may be because the hieroglyphs were painted with a variety of different

colours, that Egyptian blue was mixed with another pigment and only the areas which did not

mix fully and still remain accessible to the luminescence-inducing light are emitting

luminescence, or that either through weathering or conservation attempts the pigment has

been almost completely removed.

The same can been seen in Figures 344 to 347 from AN1893.1-41(114), limestone

architectural fragments from Akhetaten inscribed with the cartouches of Akhetaten and

Nefertiti facing those of the Aten from the 18th Dynasty. In both these objects the pigment is

only present in the inset hieroglyphs, not the surrounding striped decoration, unlike the Old

Kingdom example of AN1885.504 which only had the pigment present in the striped

decoration. It is interesting to note that according to Baines (1985: 283), blue does not

symbolise anything in Egyptian texts, unlike black, red, yellow or green pigment which all

have symbolic purposes. This could be why there is no apparent preference for blue pigment

being used specifically on the cartouches or the other hieroglyphs, but instead a faint

presence of blue on almost all of the inset hieroglyphs.

A few fragments of blue painted pottery from Tell el-Amarna, from the 18th to 20th

Dynasties were imaged because Egyptian blue has been used on pottery (Riederer, 1986: 23),

and the Amarna period, which the pottery fragments came from, was at the height of

Egyptian blue use. However, as seen in Figure 349, there is no luminescence being emitted

!


from the fragments that would indicate the presence of Egyptian blue, only a faint

luminescence of the whole image provided by the 850 nm filter that occurs when there is no

IR radiation detected and the image is being recorded under fluorescent lights, as were used

in the stores of the Ashmolean Museum where this image was recorded.

Three objects from the Third Intermediate Period were tested. The first of which was a

limestone stele recording a series of oracles delivered by the god Seth, AN1894.107A, from

the Dakhla Oasis in the 22nd Dynasty. Curious results were observed and can be seen in

Figures 350 to 353. The whole stele was imaged and did not appear to emit luminescence

except for a small amount in the upper section, seen in Figure 353. It appears that the left

outline of the dress, and possibly hair, of the woman second from the left were once painted

blue; there are also a few small areas of blue present under the table and on the floor in the

middle of the upper part of the stele. The stele is quite weathered and damaged which could

be why only these small traces have survived to the present day, or it is possible that the

presence of Egyptian blue in these areas could have been deliberate. However, it is not likely

that only these very small sections would have been painted blue; unlike QCL113 which

recorded blue in the wesekhs of the three figures depicted, the blue pigment detected here

does not make up a complete object (such as a wesekh), only a partial, uneven outline.

Therefore, it is likely that weathering or conservation attempts have in some way prevented

the rest of the pigment from being detected.

The Shrine of Taharqa, AN1936.661, from the Kingdom of Kush in the 25th Dynasty

presented some interesting information when tested with the camera. The three main walls of

the freestanding temple were tested, with close attention given to the upper bodies and heads

of the figures depicted and the raised hieroglyphs, where the pigment would likely have been

used. The east wall portrays King Tahaqra and the gods of Thebes: the human-headed Amun-

Re, Mut, Khonshu, and Montu. The north wall portrays King Taharqa standing before

Sekhmet and Nefertum-Horakhty, the other two gods of the Memphite triad. Lastly, the west

wall portrays King Taharqa before the ram-headed god Amun-Re and the goddesses Anukis

Nethy, Satis, and Anukis Ba.

The hieroglyphs did not emit luminescence, and out of all of the figures of humans and

gods on the shrine only the ram-headed Amun-Re luminesced, as can be seen in Figure 368

to 385, confirming the presence of Egyptian blue. In Figures 358 to 367, it can be seen that

Amun-Re’s skin was once painted entirely blue with the exception of his ram’s head, arm-

bands, and parts of his hands and feet. His arms and legs luminesced brightly, as did his

wesekh, and uraeus, as can be seen in a composite image, Figure 418.

!


Figure 418: Composite of images taken of Amun-Re on the west wall of AN1936.661.

!However, it is interesting to note that the small top part of the uraeus worn by the

human-headed Amun-Re on the east wall also luminesced, as can be seen in Figure 377. This

could be because at one point all of the human-headed Amun-Re was painted similarly blue

as the ram-headed Amun-Re on the west wall and weathering had damaged the wall enough

that the pigment is no longer detectable except in a small part of the uraeus. However, the

small part of the uraeus which appears blue in this case is the same part of the uraeus that

appears blue on the ram-headed Amun-Re on the west wall, therefore it is possible that this

was a deliberate decision made that has to do with the god’s depiction.

Lastly, the sandstone wall, AN1936.662, depicting King Aspelta offering Ma’at to

Amun-Re, was tested because it was a later addition to the Shrine of Taharqa during the

Napatan Period (25th Dynasty). However, as can be seen in Figures 354 to 357 there was not

any blue detected on this depiction of Amun-Re or on the wall in its entirety.

Amun-Re

Normal picture of Amun-Re. Manual focusing range, +2 1/3 flash exposure

!


The literature states that Amun being painted blue is not an unknown phenomenon for a

number or reasons, discussed below, but the inconsistency of the three figures of the god

depicted on the shrine is interesting.

It is known that around the 18th Dynasty, Amun began to be often depicted with dark

blue skin, either referring to lapis lazuli or to the colour of the sky (Robins, 2008: 15). Some

scholars believe that there is an association between the skin colour of a deity and nature,

which can result in blue- or green-skinned deities; however, colours were also used to a

significant degree as parts of repeating patterns in a wider picture, so a choice of skin colour

could be lacking in any symbolism (Baines: 1985: 285). Amun was also depicted with black

skin as a symbol of fertility, as seen in the painted limestone relief in the burial chamber of

Thutmose III from the Valley of the Kings in the 18th Dynasty (D’Auria, 2005: 779).

The colour blue has also been said to represent divine truth and justice in Egyptian

times, and can be seen in concentrated use in the tomb of Tutankhamen, where Isis, Nephtys

and Nut are adorned with jewellery painted with the pigment (Ragai, 1986: 76-7). MacKenzie

(1922: 141, 161) suggests that the importance of the colour blue and the deities associated

with it intensified as Egyptian culture spread from the Nile valley; Egyptians lacked green

pigment initially, and as such, blue may have been used to symbolise the renewal of youth

and life-giving nature represented by the Nile River.

A last example of Amun being associated with the colour blue comes from a 22nd

Dynasty mummy cartonnageo from Thebes of Amen-Nestawy-Nakht, a priest of Amun: his

face is rendered gold, with details in Egyptian blue which is the traditional colour of the

god’s face according to Goldstein (1990: 14)’s understanding of Egyptian mythology.

With all of this information regarding the use of blue pigment on deities and Amun,

specifically, it is not surprising by itself that Amun-Re on the Shrine of Taharqa was painted

blue. However, it is interesting that he was the only being or thing on the shrine that was

painted blue. Surely, if his skin was painted blue to symbolise lapis lazuli, youth, fertility,

truth, justice, or godliness, as the literature suggests, then both Amun-Re’s ram-headed and

human-headed depictions should have been painted blue, or the other gods and goddesses

should have also had some blue-element to them to symbolise their divinity, their connection

to nature, their fertility, and so on. Therefore, it is odd that none of the other gods or

goddesses (or human-headed Amun-Re) were painted blue as they too must have symbolised

some of those traits. Therefore, this possibility of godly connection to the colour blue must be

dismissed.

!


It is possible that there is some significance that the ram-headed Amun-Re, and not the

human-headed Amun-Re was painted blue for some reason that was important to the

Egyptians that is not known today, perhaps due to the nature of animal symbolism in

Egyptian culture. However, here as well there is a problem that causes this possibility to be

rejected as well: there are two other animal-headed gods present on the shrine and neither of

them are blue.

There is also the possibility that he was painted blue as part of a repeating pattern, as

Baines suggests happens in similar paintings, and not for a more symbolic reason. However,

this possibility must be discarded as well since there is not blue pigment present anywhere

else on the quite large shrine, where there was ample opportunity to paint anything else blue.

One reason for the lack of blue pigment anywhere else on the shrine may be weathering

or conservation attempts, but it is strange that no small traces of blue survived anywhere else,

as in AN1893.1-41(167) and AN1893.1-41(114) which are both from the same period and

showed small amounts of unevenly distributed blue pigment that would make sense if blue

pigment had been present, but then was mostly scraped away or damaged somehow.

In summation, there is no definite answer at the moment about the strange

inconsistency of blue paint on the depictions of Amun-Re on the Shrine of Taharqa. Further

study could answer some of these questions if this technique was used on other depictions of

Amun-Re on shrines from this period as for the most part the literature spoke of different

mediums on which Amun was depicted.

4.6 Near East objects from the Ashmolean Museum discussion

Two pieces were examined from the Near East, a partial inscription, ANLOAN109.1,

from the ninth century BCE, and AN1971.994, a stone relief from the sixth-seventh century

BCE that shows captives and loot from a Babylonian city during a raid by a river. The

inscription was tested to see if Egyptian blue might have been used similarly to how it was in

Egypt: pressed into inset writing; however, as seen in Figure 389, it did not luminesce. This

could be because blue pigment was not used in inset writing in the Near East, or because a

different blue pigment was used instead, such as lapis lazuli.

Egyptian blue was used in Mesopotamia as early as the Ur III period, which is

equivalent to around the Egyptian 11th Dynasty according to Tomabechi (1983: 128), but

Chiari and Scott (2004: 230) argue that it was widely used throughout the Middle East from

around 3600 BCE. In support of this, Partington (1950: 77) states that glass was found in

!


both Egypt and Mesopotamia from before 3500 BCE in the form of beads, and a large piece

of blue glass was found in Mesopotamia from 2400 BCE. Therefore the technology of how to

produce Egyptian blue would have existed and could have been used on objects such as the

ones tested at the Ashmolean Museum.

Both archaeological and textual evidence for lapis lazuli begin to dwindle by the

second millennium BCE when Egyptian blue began to be more prominently used

(Tomabechi, 1983: 128). Lapis lazuli was actually quite rare, according to Moorey (1994:

89), and there are only ten graves containing it even though there is evidence that it was

imported from Afghanistan in a semi-processed state. This suggests that it might have been

traded away from the area and was not often used in funerary rituals.

Since the stone relief was of later construction, the river illustrated on it was more

likely to have been painted using Egyptian blue pigment instead of lapis lazuli since it was in

more prominent use at that stage, but it did not emit luminescence, as seen in Figure 387.

Either the river was never painted blue, or was painted using lapis lazuli.

4.7 Graeco-Roman objects from the Ashmolean Museum discussion

None of the Graeco-Roman objects tested at the Ashmolean Museum showed

luminescent properties. They ranged from two standing marble statues from 200-50 BCE, to

a sarcophagus lid panel from 175-225 CE, to a marble pilaster from 175-225 CE, to two

seated marble statues from 1-200 CE, to a standing marble statue from 120-150 CE.

Egyptian blue was widely used in Graeco-Roman times on wall paintings and statues

(Smith and Plantzos, 2012: 172) and was used from the seventh century BCE to the fourth

century CE (Bradley, 2009: 431). In fact, the introduction of life-size stone sculptures in the

mid-seventh century BCE most likely came from Egypt since they were they only

neighbouring country producing similar statues at that time; the Greeks took from the

Egyptians the standing and seated poses of life-size statues, and used similar techniques to

decorate the statues (Coldstream, 1993).

The coating of sculptures in pigments in particular has been observed in the draped

parts of the statues (Bradley, 2009: 429). As such, it would be expected to find Egyptian blue

on the Graeco-Roman statues at the Ashmolean Museum. However, the grooves and folds of

the statues’ drapery which likely were coated in Egyptian blue pigment, as well as other

pigments, were often left untreated by people concerned with colour preservation after

excavation (Ridgeway, 1999: 107); this could account for the lack of luminescence detected

!


in the current study. Additionally, excavation methods in general and cast modelling had a

tendency to destroy traces of pigment (Bradley, 2009: 431).

The drapery of the two seated women: Michaelis.31 and Michaelis.32 would likely

have bright pigments on them, but as can be seen in Figures 399 and 401, no Egyptian blue

has survived to the present day. The same can be said of Michaelis.113 and Michaelis.111,

which would likely have been painted blue and red, as most mouldings were painted at that

time (Ridgeway, 1999: 108).

It is possible that the statues imaged at the Ashmolean Museum were never painted

blue, but it is more likely that the tendency of collectors and conservators over the years to

over-clean Graeco-Roman statues has removed all traces of Egyptian blue.

4.8 Romano-Egyptian objects from the Ashmolean Museum discussion

Of the six mummy portraits tested, none emitted luminescence, as can be seen in

Figures 404 to 417. This may be due to a lack of Egyptian blue pigment, to their weathered

state, or to the binding medium used which may have affected the ability for the camera to

detect the presence of the pigment, as will be discussed below.

All mummy portraits tested appear to be lightly luminescent; this can be seen as a light

pink colour being emitted from the mummy portrait, and not the surrounding area, which

appears black. This all-over light luminescence is an anomaly not present when testing any

other object at the Ashmolean Museum; the other objects tested produced images that were

black with only the Egyptian blue pigment and the control emitting a bright pink

luminescence. Therefore, it is of interest that the mummy portraits produced light

luminescence from all areas of each portrait.

It is possible that the greatly weathered state of the mummy portraits at the Ashmolean

Museum was what affected the camera’s ability to detect Egyptian blue pigment. The Getty

Institute has preformed similar tests using almost the same set up of the camera and filters

and has achieved good results, currently unpublished, with detecting the pigment, which is

why the lack of a similar response by the mummy portraits in the current study seems

strange. The mummy portraits they have tested, however, appear to be better preserved,

which could be what has caused their good results, and this study’s poor results. The camera

set up used by The Getty Institute included the use of two flashes, each with two Colour

Correction filters which they have said darkens the whole image so only the luminescence

from the Egyptian blue pigment appears. This is not likely to be the reason their results are

!


different, since the rest of the objects tested in this study were easily and clearly detected by

the camera with its set up of only one flash and one Colour Correction filter, it is therefore

unlikely that the different set up would have made a difference in the case of the mummy

portraits at the Ashmolean Museum. It should be stated that it is also possible that there was

no Egyptian blue pigment ever present on the mummy portraits tested, but this is unlikely

considering the faint luminescence of the mummy portraits, even if that luminescence did not

behave as expected.

To understand why the mummy portraits in this study reacted the way they did, it is

important to understand more about the medium. Mummy portraits are portraits of the

deceased done in encaustic on wood panels or linen cloth; nearly all examples of these

mummy portraits have been damaged by weathering due to poor burial conditions or

mummification practices (Corcoran and Svobada, 2011: 18). According to ancient writers,

encaustic was a wax-based painting technique used on wall paintings, wood, canvas,

sculptures, and other materials; the exact composition of this wax paint was not divulged in

ancient literature, though modern scientists have theorised two types of encaustic: a hot

beeswax applied in a molten state, and a cold beeswax treated with alkali (Cuni et al, 2012:

659).

While hot wax colours are generally believed to have been used on contemporary

mummy portraits, there have been no chemical analyses done which prove this (Cuni et al,

2012: 659-660). Therefore, scientists widely believe that cold beeswax saponified with an

alkali, called Punic wax, was used and added in small amounts to a conventional medium

such as oil, egg, gum, or glue to prevent cracking (Cuni et al, 2012: 660). This process,

described by Pliny the Elder, included melting the pigment with beeswax to around 95° C

(Miliani et al, 2010: 708). As this temperature is much lower than the 800-900° C required to

synthesise Egyptian blue, this melting process would not likely have had any effect on the

composition of Egyptian blue which may have altered it enough to stop it from reacting to IR

radiation the same way. However, the inclusion of an alkali may have had some affect on the

Egyptian blue due to the firing process of producing Egyptian blue which often caused a

migration of alkali flux to the surface of the pigment (Wiedemann, 1998: 198), though this is

unlikely to have affected the pigment so much that it was unable to be induced to emit

luminescence. The presence of beeswax on the mummy portraits may also be attributed to

nineteenth century CE restoration (Aliatis et al, 2010: 1541), during which time the chemical

makeup of the mummy portraits could have been altered in such a way which might have

distorted the camera readings.!

!


There are a few varnishes and resins which emit strong luminescence when using

visible excitation wavelengths, such as in the current study (Edwards et al, 2004: 787). This

may have affected the readings of the camera, and as such, it is important to investigate the

likely other materials present to fully understand the strange readings of the mummy portraits

in the current study.

A final consideration is the studies done with FTIR absorption bands: the study done by

Cuni et al (2012: 666) found that the FTIR absorption bands characteristic of beeswax

included: 2914, 2849, 1733, 1560, 1170, 954, 915, 780 and 720 nm. The study conducted by

Mirti et al (1995:441-442) observed that the FTIR absorption bands of characteristic of

Egyptian blue appeared at: 1230, 1160, 1056, 1008, 800, 755, 664, 595, 521, and 484 nm;

Salvado et al (2005: 3447) measured similar absorption bands. These numbers are not close

to overlapping, and as such, it is unlikely that beeswax would have negatively affected the

camera’s ability to properly excite and detect Egyptian blue. Miliani et al (2010: 706)

concurs, and states that the binder on the portraits has no effect on the band position of

absorption or emission spectra.

At the current time, there are no firm conclusions that can positively be reached on the

strange reactions of the mummy portraits at the Ashmolean Museum as at present, none of

the answers suggested by the literature seem likely to have caused the strange phenomenon of

all-over faint luminescence on all the mummy portraits tested in the current study; further

testing is required to fully understand these results.

4.9 General discussion and suggested further study

Testing at the Ashmolean Museum presented the opportunity to test objects from

different time periods and regions. As can be seen, the camera proved that it is possible to

detect where Egyptian blue once was, many years ago, which is visibly absent today.

Damage to the artefact does affect the image the camera records, as in QCL113 where a

diagonal line of damage cuts across the writing and distorts the writing at certain points; in

this case, the Egyptian blue is unable to be properly excited and detected as they have been

too severely worn down in areas of deep damage. Though it has yet to be determined if this is

the primary cause of the poor results from the Romano-Egyptian objects, it is very likely that

weathering on the mummy portraits caused a lack of luminescence emitted by the Egyptian

blue which was likely present at least in small amounts. This introduces a problem with

detection: if an object has been too badly damaged, the Egyptian blue pigment will no longer

!


be present in enough quantity and strength to emit luminescence that the camera can detect.

This problem can occur not only due to natural damage sustained by weathering over the

years, but also to later applications of colour such as was done during the nineteenth century

CE (Jenkins, 2006: 38), and to overzealous museum conservation; this is apparent in the

Graeco-Roman statues tested which most likely had Egyptian blue present in ancient times,

but was not detected in this study.

Future work could be done with conservation to see what techniques would completely

or partially remove all detectable traces of Egyptian blue. This would help make clear if

certain objects which only had very sparse, unconnected traces of Egyptian blue, such as

AN1893.1-41(167), AN1893.1-41(114), and AN1894.107A, originally only had this amount

of Egyptian blue, or if it there was originally more pigment that was lost over time to

weathering, or if it was conservation attempts which caused the pigment to be almost

completely removed. These tests could help scholars understand more about the use of

pigments in ancient Egypt.

Binding media or overlaid material should not affect the camera’s ability to discern the

presence of Egyptian blue, since the control tests were all run with pieces of pigment

suspended in resin and there had been no negative effect, but further testing could be done to

see if certain other materials might affect the camera’s results. Some stelae, such as

AN1894.107A, had been overlaid with a protective material by conservators, which could be

the reason for the negative results with the camera’s detection of Egyptian blue; it is also

possible that a binding medium could be affecting the camera’s ability to properly detect the

pigment.

Further work could be done on the Shrine of Taharqa as well: closely imaging every

part of the shrine could produce small traces of Egyptian blue that was missed due to time

constraints on the current study. Also, using this technique on depictions of the ram-headed

Amun-Re on other objects could also be undertaken to see if this blue-skinned Amun-Re is a

solitary occurrence, or part of a larger phenomena that may indicate something previously

unknown about the god’s depiction.

Lastly, further work should be undertaken on the mummy portraits tested to determine

why they all emitted an even, faint luminescence.

!


Chapter 5: CONCLUSION

The aim of this project was to construct, finesse, and test on museum artefacts, a

camera that can detect the presence of Egyptian Blue pigment. To do so, control conditions

were tested, the difference between recording images in the light and the dark were tested, the

difference between recording images in direct and in indirect sunlight were tested, eighty

minerals were tested, and finally twenty-five artefacts at the Ashmolean Museum were tested

for the presence of Egyptian blue pigment.

The study found that when properly utilised, the modified camera is able to detect the

presence of Egyptian blue pigment whether or not it is visible to the human eye, in dark and

light conditions, gaining the same result, which advances the understanding of this technique

gained by previous studies. However, both direct and indirect sunlight render the technique

unusable.

The minerals tested emitted no luminescence, confirming the absence of Egyptian blue.

The objects from the Ashmolean Museum provided a range of information regarding

the use of Egyptian blue during different time periods and regions. The Middle and New

Kingdom of Egypt provided the most examples of detectable Egyptian blue pigment, though

this only reflects the objects tested. The objects tested from the Near East and the Graeco-

Roman period did not emit luminescence. The results gained during the study ranged from

the expected (Egyptian blue pigment detected that was pressed into inset hieroglyphs on

stele) to the unexpected (the ram-headed Amun-Re being the only figure or object depicted

on the Shrine of Taharqa to emit luminescence) to the bizarre (the all-over faint luminescence

that was emitted from every mummy portrait tested).

By utilising literature, the presence of Egyptian blue in the current study has been

discussed in contexts of contemporary objects and expected results from previous studies

and, for the most part, conclusions were drawn, although some questions still remain. Further

study should be undertaken to better understand the results, focusing mainly on whether

conservation attempts over the years have destroyed or distorted the presence of Egyptian

blue pigment, or if binding materials may have a negative affect on the workability of this

technique.

!


BIBLIOGRAPHY Accorsi, G., Verri, G., Bolognesi, M., Armaroli, N., Clementi, C., Miliani, C. and Romani, C.

(2009) ‘The exceptional near-infrared luminescence properties of cuprorivaite (Egyptian blue)’, Chemical Communications, no. 23, pp. 3393-3394.

Aliatis, I., Bersani, D., Campani, E., Casoli, A., Lottici, P.P., Mantovan, S., and Marino, I-G (2010) ‘Pigments used in Roman wall paintings in the Vesuvian area’, Journal of Raman Spectroscopy, vol. 41, pp. 1537-1542.

Baines, J. (1985) ‘Color terminology and color classification: ancient Egyptian color terminology and polychromy’, American Anthropologist, New Series, vol. 87, no. 2, pp. 282-297.

Berke, H. (2002) ‘Chemistry in ancient times: the development of blue and purple pigments’, Angew. Chem. Int. Ed. 41, vol. 14, pp. 2483-2487.

Berke, H. (2006) ‘The invention of blue and purple pigments in ancient times’, Chemistry Society Reviews, vol. 36, pp. 15-30.

Berke, H. and Wiedemann, H.G. (2000) ‘The chemistry and fabrication of the anthropogenic pigments Chinese blue and purple in ancient China’, EASTM, vol. 17, pp. 94-120.

Bianchetti, P., Talarico, F., Vigliano, M.G., and Fuad Ali, M. (2000) ‘Production and characterization of Egyptian blue and Egyptian green frit’, Journal of Cultural Heritage, vol. 1, pp. 179-188.

Bourheroura, S., Berke, H., and Wiedemann, H.G. (2001) ‘Ancient man-made copper silicate pigments studied by raman microscopy’, Chimia, vol. 55, pp. 942-951.

Bradley, D. (2003) ‘Micro-Raman Reveals “True Blue”’, American Chemical Society, pp. 17-21.

Bradley, M. (2009) ‘The importance of colour on ancient marble sculpture’, Art History, vol. 32, no. 2, pp. 427-457.

Bredal-Jorgensen, J., Sanyova, J., Rask, V., Sargent, M.L., and Therkildsen, R.H. (2011) ‘Striking presence of Egyptian blue identified in a painting by Giovanni Battista Benvenuto from 1524’, Anal. Bioanal. Chem., vol. 401, pp. 1433-1439.

Casadio, F. and Toniolo, L. (2001) ‘The analysis of polychrome works of art: 40 years of infrared spectroscopic investigations’, Journal of Cultural Heritage, vol. 2, pp. 71-78.

Chiari, G. and Scott, D. (2004) ‘Pigment analysis: potentialities and problems’, The International Journal of Mineralogy, Crystallography, Geochemistry, Ore Deposits, Petrology, Volcanology and applied topics on Environment, Arcaheometry and Cultural Heritage, vol. 73, pp. 227-237.

Coldstream, J.N. (1993) ‘Fellowship lecture – early Greek visitors to Egypt and the Levant’ Institute for the Study of Interdisciplinary Sciences, The Journal of the Ancient Chronology Forum.

Colinart, S. and Menu, M. (eds.) (1998) La couleur dans la peinture et l'Émaillage de !l'Égypte ancienne, Bari: Edipuglia srl.

Corcoran, L.H. and Svobada, M. (2010) Herakleides A Portrait Mummy from Roman Egypt, Los Angeles: J. Paul Getty Museum.

Cuni, J., Cuni, P., Eisen, B., Savisky, R., and Bove, J. (2012) ‘Characterization of the binding medium used in Roman encaustic paintings on wall and wood’, Anal. Methods, vol. 4, pp. 659-669.

D’Auria, S. (2005) ‘A major exhibition of funerary art from Egypt’, American Journal of Archaeology, vol. 109, no. 4, pp. 777-782.

Daniels, V., Stacey, R., and Middleton, A. (2003) ‘The blackening of Egyptian blue’, The

!


British Museum Conservation science and analytical chemistry group report, pp. 1-29.

David, A.R., Edwards, H.G.M. and Farwell D.W. (2001) RRaman spectroscopic analysis of ancient Egyptian pigments’, Archaeometry, vol. 43, pp. 261-273.

Davies, W.V. (ed.) (2001) Colour and painting in ancient Egypt, London: British Museum Press.

Delamare, F. and Guineau, B. (2000) Colour making and using dyes and pigments, Longon: Thames and Hudson.

Edreira, M.C., Feliu, M.J., Fernandez-Lorenzo, C. and Martin, J. (2003) ‘Spectroscopic study of Egyptian blue mixed with other pigments’ Helvetica Chimica Acta, vol. 68, pp. 29-49.

Edwards, H.G.M., Jorge Villar, S.E., and Eremin, K.A. (2004) ‘Raman spectroscopic analysis of pigments from dynastic Egyptian funerary artefacts’, Journal of Raman Spectroscopy, vol. 35, pp. 786-795.

El Goresy, A., Jaksch, H., Razek, M. Abdel, Weiner, K. (1986) Ancient pigments in wall paintings of Egyptian tombs and temples: an archaeometric project, Heidelberg: Max-Planck-Institut für Kernphysik.

Fitzhugh, E.W. (ed.) (1986) Artists’ pigments a handbook of their history and characteristics, vol. 3, New York: National Gallery of Art.

Gaetani, M.C., Santamaria, U. and Seccaroni, C. (2004) ‘The use of Egyptian blue and lapis lazuli in the Middle Ages: the wall paintings of the San Saba Church in Rome, Studies in Conservation, vol. 49, no. 1, pp. 13-22.

Green, L. (2001) ‘Colour transformations of ancient Egyptian pigments’, in Davies, W.V. (ed.) Colour and painting in ancient Egypt, London: British Museum Press.

Goldberg, P. (ed.) (1966) Luminescence of inorganic solids, New York: Academic Press Inc. Goldstein, S.M. (1990) ‘Egyptian and near eastern art’, Bulletin (St. Louis Art Museum), New

Series, vol. 19, no. 4, pp. 1-52. Hatton, G.D., Shortland, A.J. and Tite, M.S. (2008) ‘The production technology of Egyptian

blue and green frits from second millennium BC Egypt and Mesopotamia’, Journal of Archaeological Science, vol. 35, pp. 1591-1604.

Hodgson, L. (1936) ‘Egyptian blue frit’, Papers, Society of Mural Decorators and Painters in Tepera, vol. 3, pp. 36-38.

Jenkins, I. (2006) Greek architecture and its sculpture, Harvard: Harvard University Press. Laurie, A.P. (1913) ‘Ancient pigments and their identification in works of art’, Archaeologia,

LXIV, pp. 315-336. Laurie, A.P. (1910) Materials of the Painter’s Craft, London: T.N. Foulis. Laurie, A.P., McLintock, W.F.P. and Miles, F.D. (1914) ‘Egyptian blue’, Proceedings of the

Royal Society, vol. 89, pp. 418-429. Lazzarini, L. (1982) ‘The discovery of Egyptian blue in a Roman fresco of the Mediaeval

period (ninth century A.D.)’, Studies in Conservation, vol. 27, pp.84-86. Lee, L. and Quirke, S. (2000) ‘Painting materials’, in Nicholson, P.T. and Shaw, I. (eds.)

Ancient Egyptian materials and technology, Cambridge: Cambridge University Press. Lluveras, A., Torrents, A., Giraldez, P. and Vendrell-Saz, P. (2010) ‘Evidence for the use of

Egyptian blue in an 11th century mural altarpiece by SEM-EDS, FTIR and SR XRD (Church of Sant Pere, Terrassa, Spain)’, Archaeometry, vol. 52, pp. 308-319.

Lucas, A. and Harris, J.R. (1962) Ancient Egyptian Materials and Industries, London: Kessinger Publishing.

MacKenzie, D.A. (1922) ‘Colour symbolism’, Folklore, vol. 33, no. 2, pp. 136-169. Madkour, F.S. and Khallaf, M.K. (2012) ‘Degradation processes of Egyptian faience tiles in

!


the step pyramid at Saqqara’, Procedia – Social and Behavioral Sciences, vol. 68, pp. 63-76.

Miliani, C., Daveri, A., Spaabaek, L., Romani, A., Manuali, V., Sgamellotti, A., and Brunetti, B.G. (2010) ‘Bleaching of red lake paints in encaustic mummy portraits’, Appl Phys A, vol. 100, pp. 703-711.

Mirti, P., Appolonia, L., Casoli, A., Ferrari, R.P., Laurenti, E., Amisano Canesi, A., and Chiari, G. (1995) ‘Spectrochemical and structural studies on a Roman sample of Egyptian blue’, Spectrochimica Acta., vol 51A, no. 3, pp. 437-446.

Moorey, P.R.S. (1994) Ancient Mesopotamian materials and industries the archaeological evidence, Oxford: Eisenbrauns.

Nicholson, P.T. with Peltenburg, E. (2000) ‘Egyptian faience’, in Nicholson, P.T. and Shaw, I. (eds.) Ancient Egyptian materials and technology, Cambridge: Cambridge University Press.

Nicholson, P.T. and Shaw, I. (eds.) (2000) Ancient Egyptian materials and technology, Cambridge: Cambridge University Press.

Partington, J.R. (1950) ‘Presidential address: the history of ancient technology’, Bulletin of the British Society for the History of Science, vol. 1, no. 4, pp. 73-78.

Pezzati, L. and Salimbeni, R. (eds.) (2009), O3A: Optics for Arts, Architecture, and Archaeology II, vol. 7391, SPIE.

Plantzos, D. (2012) ‘Wall- and panel-painting’, in Smith, T.J. and Plantzos, D. (eds.), A companion to Greek art, vol. 1, Oxford: Wiley-Blackwell.

Pozza, G., Ajo, D., Chiari, G., De Zuane, F. and Favaro, M. (2000) ‘Photoluminescence of the inorganic pigments Egyptian blue, Han blue and Han purple’, Journal of Cultural Heritage, vol. 1, pp. 393-398.

Pradell, T., Salvado, N., Hatton, G.D. and Tite, M.S. (2006) ‘Physical processes involved in production of the ancient pigment, Egyptian blue’, J. Am. Ceram. Soc., vol. 89, pp. 1426-1431.

Ragai, J. (1986) ‘Colour: its significance and production in Ancient Egypt’, Endeavour, New Barbs, vol. 10, no. 2, pp. 74-79.

Ridgeway, B.S. (1999) Prayers in stone: Greek architectural sculpture ca. 600-100 B.C.E., Berkeley: University of California Press.

Riederer, J. (1986) ‘Egyptian Blue’, in Fitzhugh, E.W. (ed.), Artists’ pigments a handbook of their history and characteristics, vol. 3, New York: National Gallery of Art.

Rindone, G.E. (1966) ‘Luminescence in the glassy state’, in Goldberg, P. (ed.) Luminescence of inorganic solids, New York: Academic Press Inc.

Robins, G. (2008) The Art of Ancient Egypt, Harvard: Harvard University Press. Russell, W.J. (1893) Ancient Egypt pigments, Royal Institution of Great Britain. Salvado, N., Buti, S., Tobin, M.J., Pantos, E., John, A., Prag, N.W., and Pradell, T. (2005)

‘Advantages of the use of SR-FT-IR Microspectroscopy: applications to cultural heritage’, Anal. Chem., vol. 77, pp. 3444-3451.

Schiegl, S., Weiner, K. L. and El Goresy, A. (1992) ‘The diversity of newly discovered deterioration patterns in ancient Egyptian pigments: consequences to entirely new restoration strategies and to the Egyptological colour symbolism’, Mat. Res. Soc. Symp. Proc., vol. 267, pp. 831-858.

Smith, T.J. and Plantzos, D. (eds.) (2012), A companion to Greek art, vol. 1, Oxford: Wiley- Blackwell.

Smith, W.S. (1946) A history of Egyptian sculpture and painting in the Old Kingdom, Boston: The Museum of Fine Arts.

Spurrell, F.C.J. (1895) ‘Notes on Egyptian colours’, The Archaeological Journal, Second Series, LII, pp. 222-240.

!


Taylor, J.H. (2001) ‘Patterns of colouring on ancient Egyptian coffins from the New Kingdom to the Twenty-sixth Dynasty: an overview’, in Davies, W.V. (ed.), Colour and painting in ancient Egypt, London: British Museum Press.

Tilley, R.J.D. (2011) Colour and the optical properties of materials an exploration of the relationship between light, the optical properties of materials and colour, West Sussex: Wiley-Blackwell.

Tite, M.S., Shortland, A.J., Nicholson, P.T. and Jackson, C.M. (1998) ‘The use of copper and !cobalt colorants in vitreous materials in ancient Egypt’, in Colinart, S. and Menu, M. !(eds.), La couleur dans la peinture et l'Émaillage de l'Égypte ancienne, Bari: Edipuglia srl.

Tomabechi, Y. (1983) ‘Wall paintings from Dur Kurigalzu’, Journal of Near Eastern Studies, vol. 42, no. 2, pp. 123-131.

Verri, G. (2009) ‘The application of visible-induced luminescence imaging to the examination of museum objects’, in Pezzati, L. and Salimbeni, R. (eds.), O3A: Optics for Arts, Architecture, and Archaeology II, vol. 7391, SPIE.

Verri, G. (2009) ‘The spatially resolved characterisation of Egyptian blue, Han blue and Han purple by photo-induced luminescence digital imaging”’, Analytical and Bioanalytical Chemistry, vol. 394, pp. 1011-1021.

Warner, T.E. (2011) Synthesis, properties and mineralogy of important inorganic materials West Sussex: John Wiley and Sons Ltd.

Weber, F.W. (1924) Artists’ pigments their chemical and physical properties, London: D.Van Nostrand.

Wiedemann, H.G., Bayer, G. and Reller, A. (1998) ‘Egyptian blue and Chinese blue. Production technologies and applications of two historically important blue pigments’, in Colinart, S. and Menu, M. (eds.) La couleur dans la peinture et l'Émaillage de l'Égypte ancienne, Bari: Edipuglia srl.

Williams, F. (1966) ‘Theoretical basis for solid-state luminescence’, in Goldberg, P. (ed.) Luminescence of inorganic solids, New York: Academic Press Inc.

Date post:	04-Dec-2023
Category:	Documents
Upload:	soton
View:	0 times
Download:	0 times

Uncovering Egyptian Blue Pigment With Photo-Induced Luminescence

Documents