Improving Silver Recovery in Small Installations II. The Discoloration of Electrolysed Fixers

Kixers in small, automatic, processing machines are contaminated with developer solution because of (he direct transfer of film from developer to fixer. When such fixers are cleetrolytieally desilvered and recycled, the oxidation products of the developer form a brown colour that can stain the emulsion The colour is principally related to hydroquinonedisulphonate IHQDS) or its degradation products. The colouring matter can be absorbed on activated charcoal but certain resins, such as “Zerolit” FFip. are better in that they act selectively on the HQDS With infrequent additions of 300 g lots of resin to a recycled, roller-transport machine fixer, the bath can be electrolysed and maintained indefinitely, without causing strain on the emulsion. A comparison of common anode materials shows that graphite is the worst It generates coloured matter more rapidly than does stainless steel because, on graphite, the organic components of the fixer are discharged at lower potential than the inorganic. The forma...