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  1. #11

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    Thanks Nicholas for all the info about Permawash.

    I've also found that Permawash is less-than-adequate. Although I have not tested it, I cannot help but believe that their recommended treatment and washing times are also suspect. Kodak and their scientists have done trustworthy research. I'll rely on it.

    Best,

    Doremus

    www.DoremusScudder.com

  2. #12

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    I remember reading an article many years ago that washing aids such as Permewash and Orbit Bath work by using a detergent to speed the removal of thiosulfate ion from emulsions and in the case of papers also from the paper backing. HCA works by replacing the thiosulfate ions with sulfite ions. The sulfite ion is easier to wash out than the thiosulfate ion particually from papers.

    Yes, oxygen in the air will slowly oxidize sulfite ion to sulfate ion. But sulfate ion is also effective as a washing aid along with such salts as sodium citrate and sodium chloride. Sodium sulfite is used because it is more effective thasn the others.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

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  3. #13

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    It is nice to finally learn a bit about Permawash. In the old days, many people considered it to be the premium product, but I never heard any factual information about it. I never knew anybody that used or believed the recommended times though.

    To the folks who found Permawash not to work well - I assume you are talking about residual hypo tests in comparison with HCA (or similar) for the same treatment and wash times??

  4. #14
    Nicholas Lindan's Avatar
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    Quote Originally Posted by Mark Crabtree View Post
    To the folks who found Permawash not to work well - I assume you are talking about residual hypo tests in comparison with HCA (or similar) for the same treatment and wash times??
    Yes
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  5. #15

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    How long does the sodium sulfite last in powder form? I bought a 19L pack of Kodak HCA because I couldn't get anything smaller. I mix half a teaspoon just prior to using. Does the powder oxidize too, or is that only if you mix it with water?
    And the sign said, "long haired freaky people need not apply"

  6. #16

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    Sodium sulftie solid is reasonable stable. However, if you expect to take months to use it up then you may wish to transfer it to a Mason jar or some other glass container.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  7. #17
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    Originally Posted by Mark Crabtree To the folks who found Permawash not to work well - I assume you are talking about residual hypo tests in comparison with HCA (or similar) for the same treatment and wash times??



    Yes
    Could you elaborate on which tests? The one I used (and I don't have it anymore, so I can't look at which it was) said that if you used something like Permawash, then the test wouldn't be accurate because it will react with something left by it as well as with residual fixer.

  8. #18
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    HT-2 (silver nitrate & acetic acid) is the standard test.

    If Permawash caused this [or one of the dripping tests] to show a false positive then I think the news would be shouted to the rafters by Heico. People who test and are satisfied with Permawash usually have a protocol that includes 1 hr in a Versalab print washer or some such - proof only that Permawash doesn't prevent one from washing prints normally.

    Advice to not trust test results when using Permawash sounds like very dodgy advice to me.
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  9. #19
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    Can anyone recommend a test (chemistry and protocol) that will give an accurate measure of residual hypo under all processing scenarios?

    A test that works in some situations but not in others is meaningless for comparing methods.

    - Leigh
    “Wise men talk because they have something to say; fools, because they have to say something.” - Plato

  10. #20

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    Detergents do not have significant role in accelerating washing process.

    Presence of detergents should not affect the reading of silver nitrate test for residual thiosulfate. If it comes out yellow or brown, washing is inadequate.

    Don't worry about "softening of the emulsion" stuff copied and pasted from old books. If the emulsion is not too soft in the print developer and rinse or stop bath, it will be fine in plain sulfite bath used as washing aid. Use a 35mm film canister full of it in a liter of water and it should be close enough.

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