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Cyanotypes In June of 1842, Sir John Herschel invented a novel process that he called Cyanotype, for contact-printing photographic images on paper in Prussian blue – a pigment already familiar to painters for over a century. Herschel‘s process was quickly taken up for making photograms of botanical specimens by Anna Atkins, probably the first woman photographer, and author of the first book illustrated with photographs, British Algae: Cyanotype Impressions. Over the period 1843-61, Anna Atkins, and her close friend Anne Dixon, hand-printed several elegant cyanotype albums, which are now treasures of the early photographic canon.
However, cyanotype did not enjoy wide use until after Herschel’s death in 1871, when Marion et Cie (Marion and Company) of Paris marketed a cyanotype paper, chiefly for plan-copying, under the proprietary name of ‘Ferro-prussiate paper‘. Thus the word ‘blueprint‘ entered our language, to describe the first reprographic process, with its advantages of low material cost, compared with silver photography, and simple processing in water. The manufacture of blueprint paper grew rapidly into a profitable industry, becoming the dominant process of photocopying for the next 80 years.
Cyanotype has a very low ‘speed‘ compared with developed silver halides, and can only be usefully employed for making contact prints and photograms. The light-sensitive substance is ammonium ferric citrate (originally an ‘iron tonic‘). This salt, in ca. 20% aqueous solution, is mixed with ca.16% potassium ferricyanide solution, to make the sensitizer for coating plain paper. On exposure to sunlight, the ferric salt is reduced to the ferrous state, which combines with the ferricyanide to yield Prussian blue (ferric ferrocyanide). Because the unexposed sensitizer and reaction products are very soluble, the cyanotype needs nothing more than a wash in water to complete its fixation – a procedure that Herschel regarded as ideal. There are also numerous methods of toning the cyanotype image to violet, green, brown, yellow, red, or even black.
Regarding the pictorial use of cyanotype, many connoisseurs experienced aesthetic problems with its ineluctably blue images. In Britain, Peter Henry Emerson set the tone with his acerbic dictum: "No one but a vandal would print a landscape in red, or in cyanotype." (‘Naturalistic Photography for Students of the Art‘, London: Sampson Low, Marston, Searle and Rivington, 1889) So it was used largely as a cheap method for proofing the domestic negatives of hobbyist photographers. Elsewhere, the process found greater acceptance; for instance, the still-life photographs of Henri Le Secq printed in cyanotype have survived better than his silver prints. Cyanotype was used for some 19th-century documentary photography; the subjects were large-scale engineering projects, such as the construction of the Forth Bridge (1883-90) photographed by Evelyn George Carey, the cutting of the Panama Canal (1888-93), and the surveying of the Mississippi (1883-93) by Henry P. Bosse..
Despite their vulnerability to alkali, cyanotypes are archivally stable; fine specimens have endured well from the earliest era of photography, and this inexpensive process continues to attract artists today.
© Mike Ware (2006) - Used with permission