Chromal Paper
Description
“In 1912, two chemists at N.P.G. in Berlin, Rudolf Fischer (1881-1957) and Hans Siegrist (1885-1959), introduced the notion of color couplers and patented the application of Homolkas discovery. Their patent described the structure and chemistry of most modern color materials and proposed several ways of using color development, by either an additive or a subtractive process. It also described an integral tripack made by coating three emulsions sensitive to red, green, or blue on top of one another. In addition, the emulsions contained a substance necessary for the formation of each color, the ‘color formers’ (Fischer 1913). However, Fischer was unable to solve a major obstacle: dye couplers and sensitizing dyes wandered from one layer to another during processing. In spite of obvious technical difficulties, in 1914 N.P.G. commercialized a color development paper called Chromal.2 It provided unsatisfactory results and images of poor lightfastness. More than twenty years would pass before a successful integral color tripack was produced.”
(Pénichon, Sylvie (2013): Twentieth Century Colour Photographs. The Complete Guide to Processes, Identification & Preservation. London, Los Angeles: Thames & Hudson, on p. 162.)
Secondary Sources
Pénichon, Sylvie (2013): Twentieth Century Colour Photographs. The Complete Guide to Processes, Identification & Preservation. London, Los Angeles: Thames & Hudson, on pp. 161–162. View Quote
