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  1. #1

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    Longevity of BW chemistries

    I don't often process my film so after I mix it up it can sit there for quite a while. Months. I keep it in the dark accordian type bottles that I try to squeeze the air out of. Just wondering about how long developer, fixer, stop bath , hypo will last under those conditions and what I should mix up again.

  2. #2
    mts
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    Stop bath, nearly forever.

    Fixer, until it begins to smell of sulfur or shows precipitated sulfur. You can test it by clearing some unexposed film. When the time to clear more than doubles, it is spent.

    Developers are more variable. You should not store any developer that has been diluted for use. Stock solutions vary all over the map. Rodinal can be expected to keep for maybe 50 years or so--I have used some that was at least that old with good results. D-76 stock keeps pretty well too, but its characteristics will vary over times longer than 6-months to a year. Posts here give information on keeping properties of quite a few developers.

    If you have kept developers for a long while, then you should run some test strips to verify the performance. To do this, expose some of your film on a test scene--a greyscale step if you can, or a scene typical for your photography. You can either create the test strip in a time frame near to your processing time, or simply keep one frozen and then snip off a strip for testing. I generally have some of the latter in the freezer and cut off 10" or so to ensure that I get several frames of bracketed exposures.
    By denying the facts, any paradox can be sustained--Galileo

  3. #3
    Christopher Walrath's Avatar
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    If your darkroom work is sporadic as is mine presently, you might consider mixing only what you will use per session straight from concentrate. The is called 'one shot' chemistry.
    Thank you.
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  4. #4
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    Storage as powder is nearly indefinite if packaging is good. Clip test before using very old powder when you mix and dilute it. Once mixed, use stock solution within 6 months or clip test religiously. Small .5 to 1L packs can be used up quickly once mixed but still aren't as convenient as liquid as they must be mixed at higher temperatures and then cooled to room temp before using.

    My recommendation for cheap occasional use: Kodak HC-110 or Ifotec HC are stored as glycol based non-water concentrated thick syrup so they last for years even once opened. Just mix it as you need it right from the syrup for years of occasional use. If you do mix it to a stock solution in air tight bottles then use it in 6 months or clip test regularly.

    Liquid concentrates last 1-2 years unopened, clip test after that. 6 months once opened, clip test after. Easier to measure and mix than HC syrup so more convenient but doesn't last nearly as well

    Working solutions of developer last days to weeks depending on storage and the one you're using. Clip test...

    Fixer concentrate seems to last forever. I use fixer working solutions until it is slow to clear in a clip test or just looks done.

    I use indicator stop bath working solutions until it changes color or has junk floating in it.
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    i buy 7 gallons of ansco 130 at a time and it lasts in stock solution over a year.
    working strength maybe a month ...
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  6. #6
    David Lyga's Avatar
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    Whether color or B&W, the chemistry will last indefinitely if you store it in clear, plastic bottles (juice, soda). These are airtight, came out about 15 years ago, and I have metol that I bought in the early 1970s that is still good. Obviously, the metol was not always stored in these newer containers but is still good. I never have to worry about even diluted dev going bad if stored in these containers, but they must be filled up to the very rim (NO airspace). - David Lyga

  7. #7
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    Quote Originally Posted by David Lyga View Post
    Whether color or B&W, the chemistry will last indefinitely if you store it in clear, plastic bottles (juice, soda). These are airtight, came out about 15 years ago, and I have metol that I bought in the early 1970s that is still good. Obviously, the metol was not always stored in these newer containers but is still good. I never have to worry about even diluted dev going bad if stored in these containers, but they must be filled up to the very rim (NO airspace). - David Lyga
    The developers I use don't last indefinitely at all. The A stock solution of ABC pyro lasts 6 months or so in amber glass jars, the sodium sulfite B solution an even shorter period. Pyrocat HD A stock solution is good for about 6 months.

    The amidol I mix up every time I print will last about a day in the tray.
    Jim

  8. #8
    David Lyga's Avatar
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    I cannot speak for pyro or amidol. But I can for M-H and color RA4. What I mix lasts indefinitely and I can prove this as I have diluted dev a decade old, still perfect. - David Lyga

  9. #9

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    Squeezing a lot of air out, or using accordion bottles are not the best method for keeping chemicals. The accordion bottles are not air tight and the negative pressure will increase the air permeability. Stick with PET bottles or glass to maximize developer life.



 

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