GB399841A - Improvements in or relating to colouring photographs - Google Patents

Abstract

399,841. Colouring photographs. FILLERY, H., 76, Francis Road, Hounslow, Middlesex. April 13, 1932, No. 10629. [Class 98 (ii).] Photographs in monochrome are coloured by first bringing the photograph to a cold brown tone and then applying transparent dye solutions in a particular sequence. Prior to the application of the dye solutions, a swelling- agent, e.g. a mixture of saliva and alcohol, or an alcoholic solution of sodium glyco-oleate with or without a small quantity of glycerine, may be applied. A silver gaslight or bromide print is first bleached in a potassium ferricyanide bath, washed and toned brown in a sulphide of soda bath ; the final cold brown tone being obtained by toning in a bath composed of copper sulphate, ammonia, acetic acid, and water. For sepia or red-toned photographs, the sulphide bath is omitted. After washing and drying, the swelling-bath is applied and the photograph is tinted by applying aniline dye solutions ordinarily used for tinting photographs in particular strengths and in the order crimson, yellow, green, orange, grey-a mixture of blue and violet-blue, brown, crimson, scarlet, violet, indigo-a mixture of blue, scarlet, and crimson-and black-a mixture of crimson, scarlet, yellow, blue, and brown. The earlier colours may overlap, but the darker colours should be restricted to the areas concerned. According to the Provisional Specification, the dyes are applied by dipping.