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Thread: Fixer Concentrate Go Bad?

  1. #11

    Join Date
    Feb 2015
    Location
    Sheridan, Colorado
    Posts
    947

    Re: Fixer Concentrate Go Bad?

    This is an important issue. While it's true that chemicals are usually cheaper then film or paper, it's just waste to throw out chemicals that are still functional.

    It's easy to test fixer whether using film or paper. With film, as has been suggested, you can test by putting some unexposed film in the fixer -- at whatever dilution you want -- until it clears, but it is better to be more exacting. That way, you can test not only whether the fixer is OK, but how long it needs to be used and at what dilution. And you can and should test for proper fixation with paper -- since difference films and papers exhaust the fixer at different rates. For example, microfilms need much less time in the fixer (or less dilution) than, for example, Kodak 2475 Recording film. So you really should run multiple tests for all your materials.

    Here are some simple tests -- I'm surprised these have not been mentioned because they are well known -- that will save you time and money, and should be repeated occasionally -- especially if you re-use your fixer:

    Test for proper fixation (the removal of all unexposed silver by the fixer), as follows

    A. Fix, wash and dry an unexposed, undeveloped piece of the selected paper using any desired fixer, time and dilution. Normally, it is best to start with the manufacturer's recommended time and dilution rate.
    B. On the emulsion side of the paper, apply one drop of Rapid Selenium Toner concentrate.
    C. Wait two minutes.
    D. Any yellowing indicates residual silver. Increase the amount of time in the fixer (or decrease dilution) and retest until no yellowing is noticeable..

    E. Test for exhaustion of the fixer, as follows:
    1. Take two oz of the used fixer.
    2. Add two drops of test solution such as Hypocheck:
    potassium iodide 0.01g
    water 0.05ml
    F. Shake.
    G. Wait two minutes.
    H. The solution should be clear. If it displays any milkiness, the fixer is exhausted -- decrease the dilution of the fixer and run the test again using a new piece of paper.
    I. If the fixer clears, the test is passed; increase the dilution of the fixer and repeat the test until it fails.

    With these simple, cheap tests -- using small pieces of film or paper -- I use a LOT less fixer than I otherwise would.
    Last edited by xkaes; 7-Dec-2017 at 11:53.

  2. #12

    Join Date
    Jul 2016
    Posts
    1,258

    Re: Fixer Concentrate Go Bad?

    Quote Originally Posted by xkaes View Post
    For example, microfilms need much less time in the fixer (or less dilution)
    Well, microfilms, like Adox CMS 20, can be damaged easily by overfixing (highlights kaput)... Adox says it in the datasheet... and of course halide crystals are very small, with very high interface surface, CMS 20 needs 30s to 60s.

    CMS 20 is the single film I use that I find it has a critical fixing procedure.

  3. #13

    Join Date
    Sep 1998
    Location
    Oregon and Austria
    Posts
    1,918

    Re: Fixer Concentrate Go Bad?

    While fixation tests like the one xkaes describes using KRST or the analogous test with HT-2 will tell you if you are fixing adequately, they won't tell you whether your fixer has a lot of precipitate in it that can get stuck on the film emulsion and ruin your film. While fixers with some suspended particulates in it will often fix film and paper adequately, they are on the way out. The suspended particles are often too small to be easily filtered out and can not only stick to the emulsion, but, I'm convinced, also cause small areas of density difference sometimes, causing small dots in the emulsion. I'm not sure why this happens, but I've connected it with fixer particulates enough times to be fairly sure that this is the culprit. I use these tests regularly, but now toss my fixer concentrate at the first sign of sulfur particulates in solution.

    As for the potassium iodine test solutions, like Hypo-Check: they aren't nearly sensitive enough for use with papers. By the time the test starts showing a positive result, the amount of dissolved silver in the fixer is much more than acceptable for optimal permanence. These might be helpful with film fixer, where a much higher level of dissolved silver is tolerable, but then there's the time-tested clip test, which not only tells you if your fixer is good, but gives you information for determining your fixing time as well.

    Best,

    Doremus

  4. #14

    Join Date
    Jul 2016
    Posts
    1,258

    Re: Fixer Concentrate Go Bad?

    Quote Originally Posted by Doremus Scudder View Post
    but then there's the time-tested clip test, which not only tells you if your fixer is good, but gives you information for determining your fixing time as well.
    Yes... the clip test is great ! the most useful, really

    Anyway, I think, the two stage fixing it is what ensures a perfect job while maximum exploitation of the chemicals, the drawback is an additional tray there.
    Last edited by Pere Casals; 8-Dec-2017 at 06:04.

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