How long to keep chemicals?

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Hi everyone. How long can you keep chemicals in collapsible and non-collapsible containers before they are unuable? In particular, D-76, Indicator stop bath and Kodak Fixer. I know that you can keep indicator stop bath until it changes color. Do people generally reuse their chemicals or just let them go after that round of developing?

Thanks in advance! Johnny

-- Johnny Motown (johnny.motown@att.net), December 15, 2000

Answers

Go to www.kodak.com to find the technical data sheets for all these materials and follow the recommendations there.

D-76 is the most critical of those that you mention. I usually dilute it 1:1 and use it one-shot. Many people reuse fixer until it is exhausted. I prefer to use it once for the sake of consistency, but I also shoot T-Max, which exhausts fixer faster than other films.

-- David Goldfarb (dgoldfarb@barnard.edu), December 15, 2000.


Both fixer and stop are pretty much useable until they are exhausted.

Kodak does publish shelf life numbers on their data sheets or in the B&W Darkroom Handbook.

What I do for fix is drop the cut off end of the film into some fix when I first mix it. I time how long to clear. I write this on the bottle and fix for twice as long as it took to clear. I do this everytime I use it. When the time to clear take twice as long as it did with fresh fixer, I mix fresh fixer. If the last batch of negatives is important, I will fix for a minute or two in fresh fixer.

For D-76 it lasts for 6 months in a full container and 2 months in a not full container. The collapsible containers may or may not help shelf life. The plastic is thin enough that oxygen can diffuse right through them. The best for longer term storage is glass. Get a selection of sizes and either store in a bunch of smaller bottles, or as you use it move it to smaller bottles.

I reuse fix and stop for film developing. For printing, I normally toss everything at the end of the session.

-- Terry Carraway (TCarraway@compuserve.com), December 16, 2000.


Thanks for the answers!

Johnny

-- Johnny Motown (johnny.motown@att.net), December 18, 2000.


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