The autochrome plate was the first three-color photography process on the market and belongs to the group of additive color processes. The medium consists of a mosaic of colors on a glass plate, designed to be viewed using hand-held devices or projected using carbon arc lamps.
The plates were patented in 1904 by the Lumière brothers, produced and marketed starting in 1907 by the Lumière company, and a popular success until Kodachrome was released in the early 1930s. Production stopped in 1932, although the process was still used on flexible film sheets until 1955.
In this process, a glass plate coated with a latex-based varnish is covered with a thin, regular layer of grains of potato starch dyed green, blue, and red-orange. It is then laminated by a roller press developed by the Lumière brothers. Afterward, the color mosaic is coated with a layer of resin-based shellac over which is layered a light-sensitive silver-gelatin emulsion, which may be varnished as well. The plate can then be exposed from the back in the camera and then developed and reversal-processed into a positive transparency.
A process similar to autochrome was developed in the 2000s by Frédéric Mocellin, who produces color mosaic transparencies by hand on a polyester medium.
Visual glossary of photographic techniques
© ARCP / Mairie de Paris, 2013