GB565146A - Improvements relating to photographic fixing solutions - Google Patents

Abstract

565,146. Photographic fixing compositions. KODAK, Ltd. (Eastman Kodak Co., Eaton, G. T., and Crabtree, J. I.). April 23, 1943, Nos. 16827 [divided out of 565,135 under which a Specification was laid open to inspection under Sect. 91 on April 17, 1944], and 16828. [Class 98 (ii)] A fixing solution for a photographic silver salt emulsion in which the binder is other than gelatine (e.g. cellulose nitrate, acetate, or acetate-butyrate, polyvinyl acetaldehyde, propionaldehyde, or butyraldehyde acetals ; polyvinyl alcohol; polyvinyl esters, e.g. partially hydrolyzed polyvinyl acetate ; or mixed polyvinyl acetal-esters) comprises a thiocyanate (e.g. inorganic thiocyanates such as sodium, potassium, or ammonium thiocyanates or organic thiocyanates such as thiocyanocatechol) and an aliphatic organic compound containing in the molecule two carbon attached NH2 groups, e.g. thiourea or ethylene diamine. The polyvinyl acetates and other esters may contain above 71 per cent ester by weight calculated as vinyl ester. Some gelatine may be present in the binder. The solution may contain between 6 and 50 per cent of the thiocyanate and between 0.03 and 0.25 per cent of thiourea, or between 2 to 8 per cent thiourea and 0.1 to 0.5 per cent thiocyanate. With ethylene diamine, the solution may contain between 10 to 50 per cent thiocyanate and between 1 to 50 per cent ethylene diamine. The emulsion may be a silver bromide, chloride, bromiodide, chlorobromide, or chlorobromiodide emulsion, and a thiocyanate may be incorporated in the developer as described in Specification 565,135. In an example, a fixing bath contains 50 to 100 grams of sodium thiocyanate and 5 grams of thiourea per litre. Specifications 527,283, 531,579, 543,855 and 551,659 also are referred to.