SILVER-FREE PHOTOGRAPHIC IMAGES WITH COPP ER(II) COMPLEXES OF 3-BENZOYLTHIOUREA DERIVATIVES

The formation process of non-silver images in gelatine layers of silve r halide photographic materials from the silver image by an two-stage processing over copper(II)hexacyanoferrat(II) and the following comple xation by the 3-benzoylurea derivatives 2-7 have been studied. The dep endence of the non-silver image densities on the densities of the init ial silver image have been studied over a wide range of the agent conc entrations in the processing solution and processing times. The examin ation of the reaction mechanism shows that copper(II)hexacyanoferrat, copper(II)hydroxid and the corresponding complexes in a ratio of 1:1 a nd 1:2 as well as 2:2 for the derivatives for 5 and 6 are the carries of the non-silver images. The possibilities of the practical applicati on of the described process for image amplification accompanied by com plete silver recovery from the photographic layer is discussed.