GB1462927A - Rapid access metal developers - Google Patents

Abstract

1462927 Metal chelate photographic developer; replenishing developer in processing apparatus MINNESOTA MINING & Mfg CO 23 Aug 1974 [24 Aug 1973(4)] 37234/74 Headings G2C and G2X A photographic developer comprises a ferrous chelate developing agent e.g. ferrous sulphate chelated with ethylenediaminetetraacetic acid or with diethylenetriaminepentaacetic acid, together with (i) an ascorbic acid compound of Formula where X is O or NH and R is a non-interfering group, preferably an aryl group or a group R<SP>1</SP>CH 2 (CHOH) n-1 where R<SP>1</SP> is H or OH when n = 2-4 and is OH when n = 1, e.g. ascorbic acid or isoascorbic acid, (ii) an ascorbic acid compound of the above formula together with 1-phenyl-3- pyrazolidone, glycine, cysteine hydrochloride, hydroxylamine sulphate, hydroquinone monosulphonate or 4-amino-N-ethyl-N-(#-methanesulphonamidoethyl)-m-toluidine, or (iii) amidol, gallic acid, tannic acid or 2:5-di-tert-butylhydroquinone. The developer may be regenerated by contact with iron metal having a large surface area e.g. steel wool. Exposed light-sensitive photographic material may be developed by passage through a developing tank containing the above developer, a portion of the developer being withdrawn as required through an outlet which is connected to the inlet of a regenerator tank containing metal to regenerate the developer. Regenerated developer may be recycled direct to the developing tank or to a reservoir from which it may be fed in controlled amounts to the tank. A maintenance tank is used to feed replenisher liquid having the same components as the developer to the developing tank to replace developing solution which has been removed while adhering to the developed material. The system may be controlled by flow control devices and detection devices e.g. those measuring redox potential.