GB614701A - Improvements in or relating to photographic materials and processing solutions therefor - Google Patents

Abstract

614,701. Photographic emulsions and processing solutions. ELLIOTT & SONS, Ltd., HOWE, D. J. T., and LAMBIE, A. J. July 25, 1946, No. 22202. [Class 98 (ii)] Photographic emulsion and other layers and processing solutions contain as an anti-fogging, anti-bronzing addition a dithiourazole of the formula wherein R<1> and R<2> are H or alkyl, aryl, or aralkyl. Compounds specified are dithiourazole and 1-phenyl-, 4-phenyl-, 4-methyl- and 4-ethyl-dithiourazole. The compound may be incorporated in the emulsion during manufacture or by bathing the coated material, or may be incorporated in subbing, overcoating, backing, or filter layers or in the wrapping material, or in the developing, fixing, hardening or glazing solutions. The dithiourazole may be used as a water-insoluble metal salt which is decomposable by a processing bath subsequent to development. Silver, thallous, ferrie and copper salts may be used, and may be produced by double decomposition in a gelatin solution. Different quantities of dithiourazole are required for use in different layers and baths and for producing the different effects (e.g. stabilization and improvement of the maximum density). Examples are given showing the improvement in fog values under differing conditions in a gelatino silver iodobromide emulsion with the addition of dithiourazole and 1- and 4-phenyldithiourazole, the improvements in maximum density and absence of staining in hot-glazed material having silver chloride and bromide emulsions under different conditions and with the addition of dithiourazole, a dispersion of the silver salt thereof, 1-phenyldithiourazole and 4-phenyldithiourazole, the improvements in maximum density in hotglazed bromide and chloride papers supercoated with gelatin containing dithiourazole or with gelatin containing the silver salt of dithiourazole and in hot-glazed chloride paper supercoated with gelatin containing 4-phenyldithiourazole or with plain gelatin with the emulsion containing the silver salt of 4-phenyldithiourazole and the improvements in maximum density in hot-glazed chloride paper with the addition of dithiourazole or 1- or 4-phenyldithiourazole to the developer or with bathing of the material after fixation in aqueous dithiourazole. Specifications 573,105 and 573,745 are referred to.