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  1. #1
    hka
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    Ammonium Thiosulfate or Sodium Thiosulfate

    Is it possible to use Ammonium Thiosulfate instaed of Sodium Thiosulfate as Hypo in Farmer's reducer??
    What about the conversion rate??
    At the moment I have Ammonium Thiosulfate 58-60% liquid on the shelf.
    I do need 120 grams of Sodium Thiosulfate and water to make 500 ml.
    How much Ammonium Thiosulfate (in ml) do I have to add to make also a stock solution of 500 ml?
    harry

    Release, the best you can do...

  2. #2
    Michel Hardy-Vallée's Avatar
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    In theory, I would say yes, given that ammonium thiosulfate is a reducer in an acidic solution, much more so than sodium thiosulfate. That's why one should not over-fix with rapid fixer, otherwise you lose densities.

    As for the practical side, er, sorry, no idea! I just read books but I don't apply their knowledge
    Using film since before it was hip.


    "One of the most singular characters of the hyposulphites, is the property their solutions possess of dissolving muriate of silver and retaining it in considerable quantity in permanent solution" — Sir John Frederick William Herschel, "On the Hyposulphurous Acid and its Compounds." The Edinburgh Philosophical Journal, Vol. 1 (8 Jan. 1819): 8-29. p. 11

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  3. #3
    Ian Grant's Avatar
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    Try a 10% solution Harry and test it on some scrap prints. 50g/litre.

    Maybe start with a solution slightly more dilute than when using Sodium Thiosulphate.

    Ian

  4. #4
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    Ammonium thiosulfate mixed with ferricyanide is so powerful, it becomes a rapid, one-shot blix. You could totally remove your image without wanting to. I suggest careful trials.

    PE

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    Quote Originally Posted by hka View Post
    Is it possible to use Ammonium Thiosulfate instaed
    of Sodium Thiosulfate as Hypo in Farmer's reducer??
    I'd be careful with that. Potassium ferricyanide itself
    is and oxidizer. It oxidizes elemental silver into silver
    ferrOcyanide. What it will do to ammonia I couldn't
    say. You could do as some others and fix after
    the "bleach". The fix is the "bleach". Dan

  6. #6
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    Dan;

    It is safe to mix ammonia with ferricyanide, but ferricyanide is an oxidant and thiosulfate is a reducer. These mutually react and the solution decomposes. In addition, they both react with silver metal and dissolve it utterly.

    It is a coin toss as to which takes place first. Usually, the silver goes then the rest of the reactants mutually destruct.

    PE

  7. #7
    georgegrosu's Avatar
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    Harry,
    for fixer I use normal a Kodak formulas for ECN 2. (http://www.kodak.com/US/en/motion/su...sing/h24.shtml module 7 - Process ECN-2 Specifications - FORMULAS AND ANALYTICAL SPECIFICATIONS - Fixer). I use this solution for b/w or color films. Is a fast fixer. When you use Sodium Thiosulfate pentahydrate, the concentration is 200 – 250 g/1000 ml of solution for fixer.
    With Ammonium Thiosulfate (solution 58 %) you can use 185 ml/1000 ml fixer.
    Is good if you use sodium sulfite in the fixer because this component stops the reaction:
    Na2S2O3 = Na2SO3 + S (colloidal) for Ammonium Thiosulfate the reaction is similar, but is much complicate for write.
    Normal, I use two fixer: first – used and second fixer – fresh.

    George
    Last edited by georgegrosu; 10-15-2007 at 04:42 PM. Click to view previous post history. Reason: bad link

  8. #8
    georgegrosu's Avatar
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    Sorry,
    I have same problems with the Kodak link.

    George
    Last edited by georgegrosu; 10-15-2007 at 04:28 PM. Click to view previous post history.

  9. #9
    dpurdy's Avatar
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    Isn't the regular Kodak rapid fix Ammonium thiosulfate? I have been using that with Potas ferricyanide to bleach prints for a million years. Or at least 20.

  10. #10
    hka
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    Thanks. I will give it a try.
    harry

    Release, the best you can do...

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