Historical Photographic Processes Essay Example for Free

Historical Photographic Processes Essay The Cyanotype, also known as the blue print process, was invented by Sir John Herschel in 1842 and made popular in the field of photography by Anna Atkins, a British botanist and photographer, who did a series of leaf prints and published a series of limited edition books of cyanotype prints (Rosenthal). The earliest examples of cyanotype photographs, therefore, consist of prints of leaf species. Cyanotypes are named for its blue-green (cyan) hue. It uses light sensitive Ammonium iron (III) citrate and potassium ferricyanide to reproduce an image. The Division of Rare and Manuscript Collection of Cornell University explains the process in its website: A piece of paper is first sensitized with a solution of ferric ammonium citrate (an iron salt) and potassium ferricyanide (a crystalline iron salt) and dried. The prepared paper is then contact, or placed in direct contact with the negative, and exposed to sunlight until an image begins to appear on the paper (usually about fifteen minutes). As contact prints, they are always the same size as their negatives. In the final step, the print is washed in water to oxidize the iron salts and draw out the cyanotype’s brilliant blue color (A. D. White Project). Since the 1980s up to the present, the blue print process is still used by some architects and engineers because of its simple process and low cost. The Albumen Print Process The albumen print process was invented by in 1850 by Louis Desire Blanquart-Evrard and became the popular photographic printing process for the next half decade A. D. White Project). It uses the albumen in egg whites to bind photographic chemicals to paper. The process begins by mixing the albumen with iodide of potassium and water. After the mixtures has been allowed to set for some time it is poured over a glass plate (or later on, on paper) which, in turn, is immersed in a bath of nitrate of silver and glacial acetic acid to sensitize it and make it ready for exposure in the camera. The plate is removed from the camera and poured with a saturated solution of gallic acid, followed by a solution of hyposulphite of soda, and then washed over a stream of water. When dry, the picture is ready for printing (Ross). Albumen prints are prone to fading. The general tone is yellowish with cream-colored highlights and deep chocolate brown shadows (A. D. White Project). Cited Works A. D. White Project. Division of Rare and Manuscript Collection, Cornell University. 14 April 2005. http://cidc. library. cornell. edu/adw/cyanotype. htm. Rosenthal, Richard T. â€Å"The Cynotype†. Vernacular Photography. 20 March 2008. http://www. vernacularphotography. com/VPM/V1N1/the_cyanotype. htm. Ross, James. â€Å"The Albumen Process. † Albumen. http://albumen. stanford. edu/library/c19 /ross. html.