©Mike Ware 2014 Cyanomicon 1 Cyanomicon History, Science and Art of Cyanotype: photographic printing in Prussian blue Mike Ware MA DPHIL CCHEM FRSC Honorary Fellow in Chemistry, University of Manchester, UK Scientific Advisor to the National Gallery of Art, Washington, DC www.mikeware.co.uk Buxton 2014 1 ©Mike Ware 2014 Cyanomicon 2 Table of Contents Preface ............................................................................................................................... 6 1 An Introduction in Monochrome ...................................................................... 7 1.1 The legacy of John Herschel ........................................................... 7 1.2 Equivocal blue images ................................................................... 9 1.3 Acceptance of blue photographs .................................................. 11 1.4 Commercial use of blueprint ........................................................ 11 1.5 Artistic renaissance of cyanotype ................................................. 12 1.6 A rare colour in nature ................................................................. 13 1.7 Symbolic blue in art and religion .................................................. 15 1.8 Liberation from blue preciousness ............................................... 17 1.9 Colour language and coordinates ................................................ 18 2 The Invention of Cyanotype ............................................................................ 20 2.1 A brief history of Prussian blue .................................................... 20 2.2 Light-sensitivity of iron salts ....................................................... 23 2.3 The first silver photographs on paper .......................................... 24 2.4 Herschel’s research records ......................................................... 25 2.5 Anthotype and phytotype ............................................................ 26 2.6 Discovery of cyanotype ................................................................ 27 2.7 Invention of siderotype ................................................................ 30 2.8 Publication of siderotype ............................................................. 33 2.9 Misapprehension of Herschel’s processes .................................... 37 2.10 An unaccountable omission ....................................................... 40 2.11 Pursuit of photographic permanence ......................................... 43 2.12 Marion’s reappropriation ........................................................... 44 3 The Molecular Basis of Blueprinting ........................................................... 47 3.1 Introduction to the chemistry of Prussian blue ............................. 47 3.2 Molecular structure of Prussian blue ............................................ 50 3.3 Prussian blue for ion exchange .................................................... 52 3.4 Prussian blue for electrochromic displays .................................... 54 3.5 Chemical history of siderotype ..................................................... 54 3.6 Introduction to photochemical principles ..................................... 56 3.7 Chemistry of blueprinting ............................................................ 57 4 Historical Variations on Cyanotype ............................................................. 59 4.1 Herschel’s formulae ..................................................................... 59 4.1.1 ‘Proto-cyanotype’ .................................................................. 59 4.1.2 Negative-working cyanotype ................................................. 60 4.1.3 Hydrargyro-cyanotype ........................................................... 63 4.1.4 Positive-working cyanotype ................................................... 63 4.1.5 Anachronistic ‘Herschelotype’ ............................................... 64 4.1.6 Light-bleaching of Prussian blue ........................................... 65 4.2 Pellet’s process ............................................................................ 66 4.3 Survey of negative-working formulae .......................................... 68 4.4 Modifications of the cyanotype sensitizer .................................... 71 4.4.1 Robert Hunt’s ‘chromo-cyanotype’ ........................................ 71 2 ©Mike Ware 2014 Cyanomicon 3 4.4.2 John Mercer’s ‘chromatic photographs’ ................................. 72 4.4.3 Charles Burnett’s ‘cobalt cyanotype’ ...................................... 73 4.4.4 Other iron(III) salts as sensitizers ........................................... 74 4.4.5 Terry King’s ‘cyanotype rex’ .................................................. 76 4.4.6 Cyanotype using uranium salts .............................................. 78 4.5 Cyanotype diapositives on glass and film ..................................... 79 4.6 Cyanotypes on ceramics .............................................................. 80 4.7 Cyanotypes on fabrics and textiles .............................................. 81 4.8 Gel lithography: ‘true-to-scale’ process ...................................... 82 4.9 Commercial blueprint papers ....................................................... 84 5 Studies in Blue 1842-2013 ............................................................................. 91 5.1 Herschel’s use of engravings ....................................................... 91 5.2 Identifying the sources of engravings .......................................... 93 5.3 Herschel’s cyanotype tests ........................................................... 97 5.4 Cyanotypes of British algae by Anna Atkins ................................ 102 5.5 Cyanotype albums by Anna Atkins and Anne Dixon ................... 107 5.6 An anonymous cyanotype album of 1843 .................................. 110 5.7 Later botanical cyanotypes ......................................................... 111 5.8 Early pictorial studies in cyanotype ............................................ 113 5.9 Documentary and topographical cyanotypes .............................. 115 5.10 Cyanotype currency notes and postage stamps ........................ 118 5.11 Linley Sambourne’s cyanotypes ............................................... 120 5.12 Contemporary cyanotypists ..................................................... 121 6 Methodology of Cyanotype Practice ........................................................... 123 6.1 The Diaphane: a neologism ....................................................... 123 6.2 Skiology of contact printing ....................................................... 125 6.3 The processing environment ...................................................... 129 6.4 Materials and equipment ........................................................... 129 6.4.1 Paper characteristics ............................................................ 130 6.4.2 Coating paper with glass rods ............................................. 132 6.4.3 Contact-printing frames ...................................................... 135 6.4.4 Ultra-violet light sources ..................................................... 136 6.5 Making suitable silver-gelatin negatives .................................... 138 6.6 Workflow for inkjet-printed negatives ........................................ 141 6.6.1 Summary and purpose ......................................................... 141 6.6.2 Calibration of equipment and materials ............................... 142 6.6.3 Fine-tuning negative opacities ............................................ 144 6.6.4 The 'gamma slider' for tonal correction ............................... 144 6.6.5 Workflow for digital negatives in Photoshop ........................ 146 6.6.6 Short version of the workflow .............................................. 152 7 Formulae for Cyanotype Sensitizers ........................................................... 153 7.1 The traditional cyanotype process ............................................. 153 7.1.1 Making up the sensitizer solutions ...................................... 154 7.1.2 Mixing and coating .............................................................. 154 7.1.3 Printing exposure ................................................................ 154 7.1.4 Wet processing .................................................................... 155 7.2 An “improved” cyanotype recipe ................................................ 155 7.3 Process shortcomings and their remedy ..................................... 156 3 ©Mike Ware 2014 Cyanomicon 4 7.4 The new cyanotype process ....................................................... 160 7.4.1 Making up the sensitizer solution ........................................ 161 7.4.2 Use of dichromate ............................................................... 162 7.4.3 Use of surfactant ................................................................. 162 7.4.4 Choice of papers ................................................................. 162 7.4.5 Drying ................................................................................. 163 7.4.6 Addition of citric acid to prevent fogging ............................. 163 7.4.7 Negatives and exposure ...................................................... 164 7.4.8 Wet processing and contrast control .................................... 164 7.4.9 Print washing and finishing ................................................