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  1. #11

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    Quote Originally Posted by Vaughn View Post
    For Alums, I believe it would be in hours, not minutes, thus not practical for film as a pre-hardener. My experience with potassium alum has been with hardening the gelatin of carbon prints.
    Why do the alums work post development then in only a few minutes? Or do they not work very efficiently?

  2. #12
    holmburgers's Avatar
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    For what it's worth, in developing holography plates for Lippmann pictures, it's recommended to use a 10% chrome alum bath for 10 minutes before development.

    SO, with that in mind, I don't see why this wouldn't work ok for you.
    If you are the big tree, we are the small axe

  3. #13
    Rick A's Avatar
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    Quote Originally Posted by chakra View Post
    @ Rick and Ian - Yeah ... I've been wondering about Pyro developers for this purpose but I've never used them. I like rodinal with Efke films a lot ... but I should try pyro without stressing about toxicity.


    Thanks for your responses.
    The only thing I do different from other developers is wear a nitrile glove on my hand that I agitate the tank with as it leaks slightly. I buy liquid Pyrocat-HD from Formulary so no problems with dust. I don't believe there is any difference between glycol and water mix except longevity, if you use enough that isn't a problem.
    Rick A
    Argentum aevum

  4. #14
    Vaughn's Avatar
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    Quote Originally Posted by chakra View Post
    Why do the alums work post development then in only a few minutes? Or do they not work very efficiently?
    That's not my understanding, which is chemically weak, I must admit. My Alum'ed and washed carbon prints are still very soft until dry. One only soaks them in Alum for a several minutes, but they don't fully harden until dry.

    I have only used Efke films in 11x14 -- no special problems with scratches.
    At least with LF landscape, a bad day of photography can still be a good day of exercise.

  5. #15
    Ian Grant's Avatar
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    Quote Originally Posted by chakra View Post
    Why do the alums work post development then in only a few minutes? Or do they not work very efficiently?
    Told you that at the start they are in acid fixer solutions.

    Ian

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