Superadditivity Effects in the Photographic Bleaching Process

In much the same way as the development of silver halide by developer dionions e.g., hydroquinone the oxidation of developed silver by negatively charged oxidizing agents e.g., persulphate dianions, is highly activated by onium compounds that penetrate into the negative barrier layer. Positively charged oxidizing agents, however, are not activated. In addition to this colloidochemical phenomenon and again on the analogy of the hydroquinone development other regeneration phenomenons take place with reversible redox systems that possess and appropriate redox potential.