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  1. #1
    Lukas_87's Avatar
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    FIXER - ammonium or sodium thiosulfate?

    Hello,
    can anyone tell me what's the difference between ammonium thiosulfate and sodium thiosulfate fixers?
    I know that sodium thiosulfate works slower and doesn't tend to bleach the image during prolonged fixing time.

    Someone says that Ilford has stopped producing sodium thiosulfate fixers since introduction of the Delta films because sodium thio. wouldn't fix these films "completely" so a ammonium thio. rapid fixers are need for safe fixing of these film - this doesn't make sense to me but I'm being scared of any non-archival processing (I'm young so I suppose my films just have to last long time before I die) because Ilford really writes in every datasheet of its fixers that they doesn't contain any sodium thiosulfate (hypo) at all.

    Can somebody help me about that before I finally order 25 kg sack of hypo?
    Thanks.

    ...please excuse my bad english, I'm still learning...

  2. #2

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    Ammonium thiosulfate fixers are much faster, and they may wash out more easily. If you overfix (fix for too long a time), there is a chance they will bleach your prints (but not a big chance).

  3. #3
    Ian Grant's Avatar
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    You summed it up. Sodium Thiosulphate isn't as good with Tmax/Delta type films.

    Most people use Ammonium Thiosulphate fixers these days, at one time Rapid fixers used Sodium Thiosulphate and Ammonium Chloride but this is less efficient.

    Ammonium Thiosulphate or Sodium Thiosulphate are fine for archival processing of papers, you should do a test with a Sodium Thiosulphate fixer and the films you use. You can always add Ammonium Chloride to the film fixer.

    Commercial fixer like Hypam/Ilford Rapid fixer is reasonably economic.

    Ian

  4. #4
    Ian Grant's Avatar
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    Quote Originally Posted by nworth View Post
    Ammonium thiosulfate fixers are much faster, and they may wash out more easily. If you overfix (fix for too long a time), there is a chance they will bleach your prints (but not a big chance).
    Actually with some warm-tone papers it happens within 5 minutes.

    Ian

  5. #5
    sidearm613's Avatar
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    Hi Lukas,
    I'm not that much of a chemist (I'm not much of a photographer either), but FWIW, they seem to smell a bit differently, if thats of any matter. The fact is though, that if you give ANY fixer long enough, it will bleach the image. Simple fact of life, there. Sodium thiosulfate will fix Delta, but the fixer time is long. I usually fix for 10 minutes, which is a good long time. So there you have it, any fixer will fix any type of film, except for films developed in pyro, which need an alkaline fix like TF-4. Buy whatever fixer you want, and if you are worried about your negatives with Delta, over fix by several minutes, because a few minutes won't bleach the film
    David

    A Holga is an ugly woman, a Brownie is a delicious treat.

    dromanophoto.blogspot.com/

  6. #6
    sidearm613's Avatar
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    Quote Originally Posted by Ian Grant View Post
    You summed it up. Sodium Thiosulphate isn't as good with Tmax/Delta type films.

    Commercial fixer like Hypam/Ilford Rapid fixer is reasonably economic.

    Ian


    Ian, please tell me, because it is killing me, what is the difference between Hypam and Rapid Fix. I know Hypam can take a hardener, but aren't they both just ammonium thiosulfate?

    thanks
    David

    A Holga is an ugly woman, a Brownie is a delicious treat.

    dromanophoto.blogspot.com/

  7. #7
    Ian Grant's Avatar
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    It'll be the type of buffering, but for all practical purposes they are the same, an aluminium sulphate/chloride hardener needs a more acidic pH to work.

    Boric acid and Sodium Acetate are two typical pH buffers used in Fixers.

    Ian

  8. #8

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    Quote Originally Posted by sidearm613 View Post
    Hi Lukas,
    any fixer will fix any type of film, except for films developed in pyro, which need an alkaline fix like TF-4.
    When I develop film, I use our in-house Rollo Pyro developer and fix in plain sodium thiosulfate, without any issues. What lead you to believe you needed a specially forumlated fixer?

  9. #9
    sidearm613's Avatar
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    Quote Originally Posted by Dana Sullivan View Post
    When I develop film, I use our in-house Rollo Pyro developer and fix in plain sodium thiosulfate, without any issues. What lead you to believe you needed a specially forumlated fixer?
    I can't speak for Rollo Pyro, but I can speak for PMK, which will vanish to nothingness unless an alkaline fix is used. Also, it isn't particularly specialized fixer, as it will work just fine as a standard rapid fix, albiet a non-hardening one. I am by no means a pyro wizard, I have never used Rollo, Tanol, or Pyrocat, or any bizarro dev (ABC comes to mind...), but I can tell you with fair convictions that most pyro developed negatives will not take kindly to ammonium thiosulfate.
    David

    A Holga is an ugly woman, a Brownie is a delicious treat.

    dromanophoto.blogspot.com/

  10. #10
    Ian Grant's Avatar
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    Fixers like Hypam/Ilford rapid fixer are fine with Pyrocat and some other staining developers the pH at 5.2/5.4 isn't that acidic so it's not a problem. But some acid fixers go to pH 3.

    Plain hypo fixers are fine for one off or very small volumes but they aren't efficient or robust for use where there is greater volumes and work-flow simply due to their lack of buffering.

    David, you're very wrong about Ammonium Thiosulphate as it's the basis of TF-3 & TF-4 and also thealkali colour fixers some people use for B&W work with staining developers & just as a general film or paper fixer.

    BTW Hypam uses additional Boric acid as it needs greater buffering capacity to prevent possible sludging (and reduction in hardening) caused by the Aluminium Sulphate if the pH goes past 5.5

    Ian
    Last edited by Ian Grant; 06-03-2009 at 04:43 AM. Click to view previous post history. Reason: add more info

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