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Posted by jay on February 10, 2002 at 22:22:24:
I was going to start developing film at home and was wondering if there's anyway to get rid of the chemicals in the developer or the fixer without dumping it straight into the sink. also, how long can fix generally be used before being exhausted? is there any way to tell? thanks, jay
Editor's Note: Generally, black and white darkroom chemistry from home darkrooms is not a major source of sewage pollution. I would never discard photographic chemicals into a septic tank system. Black and white fixer is more damaging to the environment than developer because used fixer contains dissolved silver, a heavy metal. Some communities have organizations which will take exhausted fixer and recover the silver. Major cities such as Seattle have hazardous waste disposal sites. Color chemistry is more toxic.
Generally one gallon of freshly prepared fixer should be able to fix 100 8x10's or 100 rolls of 36 exposure black and white film before exhaustion or before the recommended 60 day expiration. I would never use fixer to exhaustion, 50 to 60 8x10's per gallon is plenty. Fixer is a lot cheaper than photographic paper inadequately fixed. When the darkroom session is done, pour the used fixer back into the bottle and mark the number of prints or rolls fixed on a label and the date the fixer was made. I believe Edwal makes a chemical which tests for fixer exhaustion. A few drops in a few ounces of fixer will produce a precipitate (solid matter) if the fixer is exhausted. Discard the sample you test.
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