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Fixers: acid vie alkaline


I have been using staining developers since the 1950s. In my experience, the presence or absence of image stain should be verified with a tranmission densitometer. Visual examination can result in an incorrect stain assessment.
 
I came across another tanning developer formula recently. This one is from Focal, and it is quite old. Since I'm still waiting for my darkroom to get built, I haven't tried it, but it may be interesting.

Focal tanning developer

Pyrocatechin 2 g
Sodium sulfite (5 percent soln.) 5 ml
Sodium hydroxide (5 percent soln.) 10 ml
Water to make 1 l

Develop 15 to 20 minutes

The developing recommendation was no doubt for old style (1950s) films.