Hippolyte Bayard, an early inventor of photography, did not limit himself to using one of the three processes he had devised. As new methods were announced, he frequently explored them. The cyanotype process was invented in 1842 by Sir John Herschel (1792-1871), the eminent British astronomer, mathematician, and chemist. The cyanotype is easily recognized by its distinctive Prussian blue background that is a result of the use of two iron salts: ferric ammonium citrate and potassium ferricyanide. Bayard made this cyanotype without the aid of a camera by laying the various fabrics, plants, and feathers directly on top of a regular piece of writing paper that had been coated with the iron salts and then dried. He probably secured his composition under a piece of glass before placing it out in the sun for five to fifteen minutes. The exposed parts of the paper turned a stunning blue while the parts covered by the objects remained much lighter verging toward white depending on the density of the materials. By washing the sheet of paper in water the developing process was stopped and the image fixed (made permanent).
Bayard was certainly not the only person who saw the potential of the cyanotype process to faithfully record plant specimens. Anna Atkins (1799–1871) and Anne Dixon (1799–1877), avid amateur botanists in England, embraced the process in 1843 and used it over the span of more than a decade to create volumes of images that documented botanical samples from around the world (see 84.XO.227 and 84.XA.1107).
Carolyn Peter, J. Paul Getty Museum, Department of Photographs2019