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  1. #1
    barbara ann's Avatar
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    Darkroom 101 - Fixer Question

    Can someone settle a disagreement re: fixers?
    I say if you put a couple of drops of Hypo Check into the fixer solution and it turns milky the fixer is exhausted and need to be replaced. My friend says not so. An actual precipitate has to form before the fixer is unusuable.
    Which one of us is correct?
    " Practicing the arts...is a way to make your soul grow." Kurt Vonnegut

  2. #2
    glbeas's Avatar
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    You are right, but with rapid fix you get a milky look that clears when shaken. If it stays milky it's bad. Instructions also say to scoop some up in a small container like a 35mm film can to test with. I always toss mine before it show up as bad so I haven't seen that in years.
    Gary Beasley

  3. #3
    Dan Henderson's Avatar
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    I always assumed that that when the hypo check turned milky that WAS the precipitate. I toss when I see the milky color


    web site: Dan Henderson, Photographer.com

    blog: https://danhendersonphotographer.wordpress.com/

    I am not anti-digital. I am pro-film.

  4. #4

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    Quote Originally Posted by FirePhoto View Post
    I always assumed that that when the hypo check
    turned milky that WAS the precipitate.
    I toss when I see the milky color.
    Yes that is the precipitate. A few exact methods
    are given for conducting the FT-1 test. I think most
    accurate are methods employing some specific amount
    of fixer and a certain strength and quantity of test
    solution. I've never read of the levels of silver in
    the used fixer. Films and RC papers can be well
    fixed in fixers very laden with silver. Not so
    with FB papers.

    I can't use the test myself as I've adopted the use
    of very dilute one-shot fix. The silver levels are so
    low as to be nearly invisible. Dan

  5. #5

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    Hi !
    The main problem with this kind of tests is that it is not quantitative.
    If you plan to get the most of your fixer, buy Tetenal fixert test stickers instead. The small tab change color according to the percentage of silver in the fixer solution. A table gives you the quite exact amount of silver into the fixer. This way you'll know if you are overusing it or not.

  6. #6
    Akki14's Avatar
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    Doesn't help with paper fix but for film i always put a cut-off bit of film into the fix and time it. as long as it clears in about 30-35 seconds (in rapid fix) it's fine. When it suddenly decides to take 55s-1m to clear, it's off and i dump it.
    ~Heather
    oooh shiny!
    http://www.stargazy.org/

  7. #7

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    What Danqu said: for resin papers and film, the fixer just needs to be active, which is easily tested with a scrap of film. Fiber papers act as a sponge, and a two-bath fix is indicated: the first bath to dissolve undeveloped silver, and the second to bring it out of the fibers and into solution. Of course, when the first bath gets tired (measured as Akki says), then dump the first bath, and use #2 as bath #1, and mix a new bath #2.

  8. #8
    barbara ann's Avatar
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    I've never heard of Tetenal fixer test stickers. Don't know if they're sold here in the US but they sound like they're just what I need. Perhaps I should have made it clear that I am developing RC paper and not film.
    " Practicing the arts...is a way to make your soul grow." Kurt Vonnegut

  9. #9
    Photo Engineer's Avatar
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    First off, never put the fixer test solution into your fixer. It will decrease the power of the fixer! You must remove a small fixed quantity of your used fixer into a glass container and then drop in a few drops of the test solution.

    You will see a YELLOW heavy cloudy precipitate form if the fixer is exhausted. A white precipitate does not indicate exhaustion.

    The fixer test solution is Potassium Iodide, and this forms as strong a bond with silver as hypo does. If there is too much silver, then the iodide wins, and you get a precipitate and if there is the right amount of hypo left, the fixer is more powerful and you get a white cloud or nothing at all.

    Why yellow? Because silver iodide is bright yellow, thats why. So if you don't see it turn yellow, it isn't forming!

    And remember this... The test solution goes bad and so must be discarded if it begins to smell like iodine or turn brown.

    PE

  10. #10

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    Quote Originally Posted by GeorgesGiralt View Post
    Hi !
    The main problem with this kind of tests is that it is
    not quantitative.
    True. And the methods of testing vary. But an useful
    semi-quantitative test may be made of it by using the
    film strip test in conjunction with the FT-1 test. Simply
    clear a film strip then use some small amount of the fix
    and test with a drop or two of the standard potassium
    iodide solution.

    If the strip test shows spent fix but the FT-1 does not
    reduce the amount of fix used for the drop test until a
    precipitate does form. Very little of the iodide is used
    in making a test solution of many many drops. May
    be more convenient than strip testing. Dan

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