GB586729A - Improvements in photographic fixing solutions - Google Patents

Abstract

586,729. Photographic fixing solutions. KODAK, Ltd. (Eastman Kodak Co., Crabtree, J. I., and Eaton, G. T.). -.June 9, 1944, No. 11097. [Class 98 (ii)] Material having a layer of a silver salt emulsion having a binder having as a predominant constituent a substance having a permeability to aqueous fixing solutions less than that of gelatine, is fixed with a solution containing a lower molecular weight aliphatic alcohol, and thiourea or a thiocyanate or both. The silver salt emulsion may be a bromide, chloride, bromiodide, chlorobromide; or chlorobromiodide emulsion having as binder cellulose nitrate, acetate, or acetate-butyrate ; or polyvinyl resins such as acetals (e.g. acetaldehyde, propionaldehyde, or butyraldehyde acetals). polyvinyl alcohol, esters (e.g. partially hydrolysed acetates) or mixed acetal-esters. The lower aliphatic alcohol may be methyl, ethyl, propyl, or butyl alcohol or ethylene glycol, and the thiocyanate may be sodium, potassium, ammonium, or tetramethylammonium thiocyanate or thiocyanocatechol. The thiourea or thiocyanate may be dissolved in a wateralcohol mixture containing between about 1 to 70 per cent by volume of alcohol. In an example, a fixing bath is formed by mixing equal parts of a 1 per cent aqueous solution of thiourea and ethyl alcohol. A thiocyanate may be incorporated in the developing solution. Specifications 527,283, 531,579, 543,855, 551,659 and 565,135 are referred to.