Response to adding sodium sulfite to developer

Yes, sulfite is a componant of several developers. One of its activities is to act as a reducing agent to keep the developing agents reduced so they can then reduce the exposed silver (lots of reduction going on there huh?). Another action that sulfite has is as a silver solvent. It's solvent activity is towards the metalic silver in the emulion. It basically disolves the surface of the developed silver grains changing their structure and look. The disolved silver can redeposit elsewhere on the silver grains again altering them. This activity occurs at high concentrations of sulfite, beyond that necessary for the preservative activity. A good example of a developer that uses both of these activities of sulfite is D76. Undiluted D76 is a highly solvent developer. Diluted 1:1, the sulfite concentration is decreased enough to decrease the solvent activity and the negatives have an entirely different character (are sharper and have more grain).

Get your self a copy of Steve Anchell's Darkroom Cookbook and a copy of Steve Anchell and Bill Troop's Film Development Cookbook. They will give you all the information you could possibly want or need about componants and formulations of developers and other reagents used in photography.

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