How long to keep fixer?

Discussion in '35mm Cameras and Accessories' started by Andrey, Jun 17, 2013.

  1. Andrey

    Andrey Member

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    I had access to chemicals through a photo club for the last while. Now I want to do more development at home.

    I have HC110 which is easy to make and I'm ok using it.

    How long does normal film fixer stay alive? How careful should I be about oxygen? Is there a more stable alternative formula? Does change of fixer influence results?

    Thanks

    Andrey
     
  2. MattKing

    MattKing Subscriber

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    Hi Andrey.

    Most photo chemistry has a data sheet that has been prepared by its manufacturer. Those data sheets usually include recommended life estimates.

    What fixer are you using or considering?
     
  3. Jesper

    Jesper Subscriber

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    You can use a piece of film to test the fix. If you develop 35mm films you can use the film lead that you cut off. The time in the fix should be about twice the time that it takes for the lead to become clear.
     
  4. Andrey

    Andrey Member

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    The club had a kodak film fixer. It worked fine for me.

    I just wanted something that doesn't expire fast for home use, because I won't use it in gallon volumes.
     
  5. Gerald C Koch

    Gerald C Koch Member

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    The manufacturer will tell you the capacity of the fixer. Keep track of how many rolls and prints you run thru it and do not exceed this recommendation unless you use a two bath system. Acid fixer will go bad with time and undergoes what is called sulfurization. The solution will turn milky as it begins to throw down sulfur. It must then be discarded.
     
  6. Andrey

    Andrey Member

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    how long does this take to happen?
     
  7. Terry Christian

    Terry Christian Subscriber

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    Unless you're talking about years, fixer and stop bath generally don't "go bad" with time the way developer will. They just expire with use, like the sulfurization Gerald C. Koch mentioned above. If you're using standard or rapid acidic fixer (sodium or ammonium thiosulfate), you'll notice that when first mixed, it has a sharp, acrid smell. With use, it'll gradually start to smell more sulfurous.

    As for capacity, a commonly used fixer, Ilford Rapid Fixer, has a listed capacity of about 24 rolls of 35mm film per liter of working solution. Again, unless you're talking about years, it shouldn't matter how long it takes for you to run that much film through it. You can store working fixer in a plastic bottle with a tight-fitting cap, just like most photo chemicals. More impermeable materials, like glass or PETE plastic, would be of course better, but you don't have to be as concerned as you would with developer.
     
  8. jnanian

    jnanian Advertiser Advertiser

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    if you have access to the same UNUSED fixer you have+use, see how long it takes to clear a 1x1"square piece of film
    when it eventually takes 2x that original time to clear the film your fixer is no longer good.
    just remember that (original) number and always use the same film to do your test ..

    have fun!
     
  9. Gerald C Koch

    Gerald C Koch Member

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    The sulfurization of fixers is dependent on the temperature. Fixer should be stored in a cool but not cold environment. This will extend its life.
     
  10. polyglot

    polyglot Member

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    It takes literally many years before sulfation will occur, and by years I mean "most of a decade". Even after sulfation has begun and there's a nice layer of white precipitate at the bottom of the fixer bottle, the fixer will still work though somewhat more slowly. If you do the clearing test and fix for twice as long as the clearing time, your negatives will basically be fine. If there is precipitate, you'll want to filter it out with a coffee filter in order to not get spots on your film though. Once the fixer starts to smell strongly of rotten-egg gas (instead of mostly vinegar), that's a sign that it's decomposing and will start sulfating soon. That begins after about 2 years in the cupboard in my experience.

    You don't need to protect fixer from oxygen in the way that you do developers (which are reducing agents and therefore very sensitive to oxidation). Just keep it in a sealed bottle in the cupboard, nice and cool but never frozen.

    FAQ for fixer capacity with normal use.

    Because fixing is to-completion and should leave nothing in the film, it doesn't matter which brand or type you use, and they're all based on thiosulfate. They all do the same thing and leave your film in the same state, i.e. with all undeveloped halides removed. Some are faster (ammonium) or slower (sodium) than others, some are easier to wash out of FB papers (alkaline fixes) but those are basically the only relevant differences. For film use, it doesn't matter which you pick as long as you follow the instructions for the one you're using.

    A 1L bottle of rapid fixer makes 5L at 1+4, which has a max capacity of 60 to 100 rolls. Say you shot a roll of B&W per month and did no wet printing, 12 rolls a year. It'd take you 5 years (at 12 rolls/L if you shoot all T-grain films) to 8 years (20 rolls/L, nominal capacity with traditional films) to use your 1L bottle to capacity; at 5 years it will be fine and at 8 years it will be definitely starting to go off but should still work OK. Those 1L bottles are pretty cheap (under $15 here in ripoff-land) and maybe you could share one with someone nearby who similarly shoots very little? Either way, the cost of fixer ($10-$15) is generally irrelevant next to the cost of the film ($500?) you process in it. If you end up chucking half out after a decade because it went off, who cares?
     
  11. pen s

    pen s Member

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    The only time I've has fixer 'go bad' was when I forgot how much film I had run through it and it just stopped working. Pulled the film out after 6 min. and it was still milky and had not cleared. Then I mixed new fixer and ran the film through again and it cleared just fine.
     
  12. Gerald C Koch

    Gerald C Koch Member

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    Once fixer starts to sulfurize it should NOT be used. If any bits of sulfur adhere to the emulsion it will be impossible to remove it without damaging the film. Fixer is cheap but film is expensive.

    Typically in Florida a fixing bath will begin to sulfurize in 9 months to a year. As I said it is based on the storage temperature of the bath.

    Whether a fixing bath is fresh or partly used has nothing to do with its sulfurization. Any acidic solution of a thiosulfate is unstable. To slow down the sulfurization process sodium sulfite is added to the fixer. Its purpose is to combine with any sulfur formed and convert it back to thiosulfate. Once the sodium sulfite has been completely used up the bath will sulfurize very rapidly.
     
    Last edited by a moderator: Jun 18, 2013
  13. Andrey

    Andrey Member

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    Thank you so much. It seems like I'm set then. :smile: