GB453674A - Colour photography and cinematography - Google Patents

Abstract

453,674. Colour photography. DOLGORUKI, E. SANDERS-, 14:, Wetherby Gardens, Earl's Court, London. Sept. 2, 1935, No. 24458. Drawings to Specification. [Class 98 (ii)] A method of producing dyestuff images for colour photography or kinematography includes the steps of subjecting an exposed emulsion to a photographic reversal process and utilizing the second metallic deposit produced by reversal to control the production of colourless portions in the emulsion by destruction of a diffused dyestuff. The emulsion may be preliminarily treated with the diffused dyestuff or a colourless or coloured body convertible into the dyestuff may be incorporated in the dyestujf prior to the first development. After development and washing the silver is removed by permanganate or bichromate and sulphuric acid or preferably the acidified solution of a ferric salt. The remaining silver halide is re-exposed to light and redeveloped. The second exposure to light may be replaced by treatment with a sodium hydro sulphite solution containing sodium bisulphite or with diamidophenol developer made alkaline with sodium carbonate. The dyestuff is destroyed at the points where there is metallic silver, either with known reducing or oxidizing reagents such as sodium hydrosulphite and potassium bromide. The second silver deposit may be replaced by mercury, copper or lead. The first silver deposit may be converted to silver iodide and the emulsion redeveloped, after exposure to light with a developer which does not reduce silver iodide. The dyestuffs used may be Chorazol Sky Blue FF or Diamine Pure Blue FF for blue-green, Diamine Fast Pink G or Benzopurpurine 10B for magenta, Mordant Yellow GG or Chrome Fast Yellow GG for yellow. Specifications 133,034, 249,530, [both in Class 98 (ii)], 395,718, 397,188, and 426,260 are referred to.