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  1. #1

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    Sodium Thiosulphate (Hypo) - Lifetime

    Does anyone know what the lifetime is of a 10% solution of Hypo? I have done some fixing of a couple of salt prints and then poured the solution back in the bottle (like I do with Rapid fixer) for re-use later. IS that OK...or should I be treating it as one-shot fixer? How can I test its suitability for re-use (eg some form of clearing test like for rapid fixer).

    Rgds

    Kal

  2. #2

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    If it is a pure Hypo-solution (no sodium sulfite), then its lifetime is max 24 hour.
    So use it and throw it away.

    Tom

  3. #3

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    It's pure, so thanks for the pointer. Rgds, Kal

  4. #4

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    Does hypo dissolve well in propylene glycol, I wonder? The CRC says it's soluble in ammonia and insoluble in alcohol, but has no position on glycol. If it was amenable to a preservative solution the same way that phenidone is, that'd be convenient. (I assume ammonia wouldn't be a useful solvent for this purpose.)

    -NT

  5. #5

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    Quote Originally Posted by Shangheye View Post
    Does anyone know what the lifetime is of
    a 10% solution of Hypo? Kal
    I regularly use straight S. Thio. at 1% to 2%
    strength for fixing prints. Strength depends on
    paper; fixer requirements vary. One-shot. Dan

  6. #6

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    Quote Originally Posted by dancqu View Post
    I regularly use straight S. Thio. at 1% to 2%
    strength for fixing prints. Strength depends on
    paper; fixer requirements vary. One-shot. Dan
    How long do you fix with that ratio? Twenty grams is about 1/10th of the usual minimum. And then there is the matter of how many prints will it fix.

    Inquiring minds want to know.

  7. #7

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    Quote Originally Posted by Paul Verizzo View Post
    How long do you fix with that ratio?
    Twenty grams is about 1/10th of the usual minimum.
    And then there is the matter of how many prints will it fix.
    Inquiring minds want to know.
    I fix for 31/2 to 4 minutes. A single fix at such a high
    dilution is all that is needed for greatest LE. The usual
    strength of a sodium thiosulfate anhydrous fixer is
    150 to 160 grams per liter; 15 to 16 percent. So,
    1% for Slavich, 10 grams per liter. Good for 3
    8x10s, each in 1/3 liter. Dan

  8. #8
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    Would welcome some thoughts as to why my Vandykes bleach out a bit when fixing in straight Hypo/sodium thiosulfate. I was under the impression that Vandykes should get darker! And yes, they do seem to be fixed :-)



 

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