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  1. #21
    hka is offline
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    Dec 2004
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    Quote Originally Posted by gainer View Post
    I thought I posted this last night. I'm glad it tidin't go through. I had a big boo boo.

    The sulfite in D-76H, besides serving as the alkali, is to keep oxidized Metol from slowing sown the reaction. Sodium or potassium ascorbate is more effective because it regenerates the oxidized Metol. If you substitute 8.8 grams of ascorbic acid or 10 grams of sodium ascorbate for the sodium sulfite and increase the borax to 25 grams, you may be quite happy with the results. You will wind up with 2.5 grams of Metol, 8.8 grams of ascorbic acid (0.05 M) and 25 grams of borax to make a liter of working solution.
    Mr. Gainer
    What about the self-life with the use of ascorbic acid. Will it be as steady als de "original" recipe?

    Release, the best you can do...

  2. #22
    gainer's Avatar
    Join Date
    Sep 2002
    The ascorbic acid is certainly oxidized by the oxygen dissolved in the water of solution, but this is mostly over with soon after mixing. It is too soon to make a guess about years, but after months of storage I see no difference. The ascorbate formed on mixture is in excess of the minimum required by a factor of about 2. Its function is not to serve as a developing agent, but to regenerate the Metol. Metol is not extremely sensitive to bromide concentration. I cannot see how the Metol-C-Borax solution could have any shorter shelf life than the D-76H.
    Gadget Gainer

  3. #23

    Join Date
    Sep 2002
    Willamette Valley, Oregon
    Medium Format
    Quote Originally Posted by gainer View Post
    Where did you get that information about
    regeneration in carbonated developers?
    I've just brought forward the thread "An Interesting Aspect ... "
    Alan Johnson's posts detail some of G. W. Crawley's work with
    non-regenerative low sulfite carbonated developers. Dan

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