FACTORS LIMITING THE RECOVERY, REGENERATION, AND REUSE OF PHOTOGRAPHIC PROCESSING SOLUTIONS

Four factors limit the extent to which photographic processing solutio ns can be recovered, regenerated, or reused: (1) the ability to collec t the solutions efficiently, (2) dilution by water or other solution c arried over from the preceding processing step, (3) exhaustion of some of the chemical components in the solutions, and (4) contamination of the solutions by reaction products or carry ver. Collection efficienc y and dilution are determined by the efficiency of the squeegees and b y the swelling of the emulsion. Exhaustion of the active components of solutions, usually the developing agent, can be offset by careful for mulation and replenishment. Halides are the most common contaminant of developers, and several techniques have been used to remove them. Fix ers and bleach-fixes are contaminated by halides, silver, and total di ssolved salts, but only the silver can be conveniently removed. Exampl es of how each of these limiting factors affect various photographic p rocesses are given.