Defender Pan-Chroma-Relief
Description
“In 1942 Defender Photo Supply Company of Rochester, New York, introduced a panchromatic matrix film called Pan-Chroma-Relief Film, which simplified the making of dye imbibition prints from original Kodachrome or Ansco Color transparencies.20 Up to that time, available matrix films for dye imbibition printing were sensitive only to blue. Making matrices from a color transparency involved two steps: printing a set of black-and-white separation negatives and, from these, a set of positive matrices. Panchromatic matrices, exposed through red, green, and blue color separation filters and developed with an etching treatment, directly produced positive matrices from color transparencies. After regular processing that produced a negative image, the matrix films were immersed in an etching solution. The solution decomposed gelatin in situ with a developed silver image, leaving the plain gelatin unaffected. This effectively reversed the developed negative silver image into a direct positive gelatin relief. Once color negatives became available, Pan-Chroma-Relief Film could also be used to directly produce matrices. In that case, a warm water wash process was used (Defender ca. 1942).21”
(Pénichon, Sylvie (2013): Twentieth Century Colour Photographs. The Complete Guide to Processes, Identification & Preservation. London, Los Angeles: Thames & Hudson, on p. 146.)
Secondary Sources
Pénichon, Sylvie (2013): Twentieth Century Colour Photographs. The Complete Guide to Processes, Identification & Preservation. London, Los Angeles: Thames & Hudson, on p. 146. View Quote
