Bichromated gelatin

Description

A photographic emulsion used in nineteenth century printing processes, such as collotypes and carbon prints. Bichromated gelatin was first described by H.F.Talbot in 1852 for use in photogravure. Bichromated gelatin paper is coated with a Gelatin emulsion that has been sensitized with Potassium dichromate. When exposed to light, the bichromated gelatin hardens proportional to the intensity of radiation. The non-exposed areas remain soft and moisture sensitive, while the exposed areas become hard and moisture resistant. Other chromate salts, such as Ammonium dichromate and Sodium dichromate, were also used.

Synonyms and Related Terms

bichromated colloid; dichromated gelatin; dichromated colloid

Resources and Citations

• The Dictionary of Art, Grove's Dictionaries Inc., New York, 1996 Comment: 'Photography'

• Luis Nadeau, Encyclopedia of Printing, Photographic, and Photomechanical Processes, Atelier, New Brunswick, 1997