why is the sodium sulfite split in this 2bath recipe??

Discussion in 'Black and White' started by gonzalo_echeverria, Nov 22, 2005.

  1. hi,

    here's the recipe...

    This formula is from Patrick Dignan's book Classic B&W Formulas.

    Solution A
    Sodium Sulfite, 35 grams - Hydroquinone, 6 grams
    Phenidone, 0.2 grams - Sodium Bisulfite, 6 grams
    Water to make, 1 liter

    Solution B
    Sodium Sulfite, 65 grams - Sodium Metaborate, 20 grams
    Or, Borax 20 grams, for results "like that of D76"
    Water to make, 1 liter

    Mr. R. W. Anderson who wrote the article, claims a true
    one stop speed boost plus "the advantages ... of
    a two bath".

    .... normally you'd have all the sodium sulfite in bath A ... right?


    what is the function of the sodium sulfite in the bath B?


    thanks.
     
  2. No, you wouldn't because the Sodium Bisulfite is already acting as a preservative for the developing agent and Sodium Sulfite in that amount in the solution would make the solution sufficiently alkaline that development would take place in the "A" bath.

    Most "true" two-bath developers work as follows:

    Film soaks in Solution A to soak up development agent. Film is then placed in alkaline solution B to actually enable development to proceed.
     
  3. thanks Al,

    so why is it in bath 'B' ?


    gonz.
     

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