While the three color process that led to modern color photography was suggested in 1851 by Physicist James Clerk Maxwell, another more complex method of producing color images was popular during the late 1800s and early 1900s. The photochrom process, a spin-off of chromolithography, used six or more ‘tint stones’ to add color to an image, creating a finished print.
Pictures created using the photochrom process look a ton like modern color images, but with a strange coloration that feels both historic and whimsical. The process was commonly used in the 20th century to create postcards of historic buildings, which are very cool, and have an artistic feel that our modern high-def images lack.
A tablet of lithographic limestone called a “litho stone” was coated with a light-sensitive surface composed of a thin layer of purified bitumen dissolved in benzene. A reversed halftone negative was then pressed against the coating and exposed to daylight (ten to thirty minutes in summer, up to several hours in winter), causing the bitumen to harden in proportion to the amount of light passing through each portion of the negative. Then a solvent such as turpentine was applied to remove the unhardened bitumen and retouch the tonal scale, strengthening or softening tones as required. Thus the image became imprinted on the stone in bitumen. Each tint was applied using a separate stone that bore the appropriate retouched image. The finished print was produced using at least six, but more commonly ten to fifteen, tint stones.
The process was invented in the 1880s by Hans Jakob Schmid (1856–1924), an employee of the Swiss company Orell Gessner Füssli—a printing firm whose history began in the 16th century. Füssli founded the stock company Photochrom Zürich (later Photoglob Zürich AG) as the business vehicle for the commercial exploitation of the process and both Füssli and Photoglob continue to exist today. From the mid-1890s the process was licensed by other companies, including the Detroit Photographic Company in the US (making it the basis of their “phostint” process), and the Photochrom Company of London.
The photochrom process was most popular in the 1890s, when true color photography was first developed but was still commercially impractical.
In 1898 the US Congress passed the Private Mailing Card Act which let private publishers produce postcards. These could be mailed for one cent each, while the letter rate was two cents. Publishers created thousands of photochrom prints, usually of cities or landscapes, and sold them as postcards. In this format, photochrom reproductions became popular. The Detroit Photographic Company reportedly produced as many as seven million photochrom prints in some years, and ten to thirty thousand different views were offered.
After World War One, which ended the craze for collecting Photochrom postcards, the chief use of the process was for posters and art reproductions. The last Photochrom printer operated up to 1970.
The first Shakespeare Memorial theatre complex, c. 1890s
Belgian milk peddlers with a dogcart, c. 1890s
Neuschwanstein Castle, Bavaria, Germany, c. 1890s
Bergen, Norway, c. 1890s
The elavated at 11th street, New York City, c. 1900
A sailboat on the Nile river in Cairo, Egypt, c. 1899
Resting Bedouins at the Grand Pyramid, Cairo, Egypt, c. 1899
A mosque in, Kairouan, Tunisia, c. 1899
State Street north from Madison Street, Chicago, Illinois
Sapphire Pools, Yellowstone National Park, Wyoming
Coolvest, Rotterdam, Holland, c. 1890s
Voorstraatshaven, Dordrecht, Holland, c. 1890s