GB725892A - Improvements in single powder photographic developers - Google Patents

Abstract

725,892. Photographic developing compositioris. KODAK, Ltd. June 26, 1953 [June 26, 1952], No. 17745/53. Class 98 (2). A single-powder photographic developing composition contains an organic silver halide developing agent, a water-soluble and photographically compatible basic ingredient comprising a hydrate of sodium metaborate containing less than 34.3 per cent of water of crystallization, and optionally boric anhydride (as a stabilizing agent) and an antifogging agent. In example 1, a thin layer of sodium metaborate tetrahydrate is dried on a metal plate at 550‹ F., and the powdered product is incorporated in a developing composition including also mono-methyl-p-aminophenol sulphate, hydroquinone, sodium sulphite, sodium bisulphate, potassium bromide, and boric anhydride. Examples 2 and 3 are similar, using the tri-, di-, and mono-hydrate and the anhydrous forms of sodium metaborate. The stabilizer and the treated sodium metaborate may be first mixed, the developing agent added and mixed, and the remaining ingredients added. The sodium metaborate tetrahydrate or the partially dried product as in example 1 may be mixed before drying with another ingredient, e.g. anhydrous sodium sulphite. The sodium metaborate tetrahydrate may be dried in an atmosphere of acidic gas, such as CO 2 , SO 2 , HC1, acetic acid, or nitrogen oxide. In examples 4 and 5, sodium metaborate tetrahydrate is treated with carbon dioxide and sulphur dioxide before incorporation in a single-powder developing composition. Specification 585,366 is referred to.