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Forming colour images in photographic silver halide materials - in the presence of a cobalt complex which catalyses the redox reaction between peroxide and developing agent cpd.
Forming colour images in photographic silver halide materials - in the presence of a cobalt complex which catalyses the redox reaction between peroxide and developing agent cpd.
Process for forming a colour image in a photographic prod. having =1 layer contg. a Ag image and an associated colour forming RDR material comprises (1) contacting the prod. with an alkaline silver bleaching soln. contg. a Co (III) complex which liberates definitive coordinates by redn., in the presence of a cpd. which forms a Ag salt and which is incapable of oxidising Ag, to form Co (II) as reaction prod. corresp. to the original Ag image. Process further comprises; (2) treating the material with an alkaline amplification soln. contg. a peroxide oxidising agent in the presence of an oxidising developer to form a mobile colour image corresp. the Ag image and (3) transferring the mobile colour image to a receptor sheet in which the peroxide oxidising agent, the oxidising developer and the colour forming agent are inert to oxidation-reduction in the absence of the reaction prod. of Co (II) acting as catalyst. The presence of the Co complex catalyses the redox reaction between the peroxide and the developing agent to form a mobile dye by oxidn. of the colour forming cpd.
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