Formula for copper based rehalogenating bleach

Discussion in 'B&W: Film, Paper, Chemistry' started by Mark Fisher, Nov 8, 2011.

  1. Mark Fisher

    Mark Fisher Subscriber

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    I am looking for a copper based bleach to use with second pass lith printing. I can't find my Tim Rudman lith book (ugh!) and I looked all over the web and I can't seem to find what I am looking for. I used some potassium ferricyanide bleach last night with some pretty interesting results, but I want to try a different bleach to see what the difference might be.

    Thanks -- Mark
     
  2. Ian Grant

    Ian Grant Subscriber

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    As a starter you could possibly use acidified Copper Sulphate and Potassium Bromide

    Something like

    Copper Sulphate (pentahydrate) 35g
    Potassium Bromide 110g
    Acetic acid (10%) 10ml
    Water to 1 litre

    Ian
     
  3. trotkiller

    trotkiller Subscriber

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    Taken from page 99 of The Master Photographer's Lith Printing Course

    Copper Sulphate 50 g
    Sulphuric Acid 6.5 ml
    Sodium Chloride 50 g
    Water to 1 L

    Dilute 1:9 for use
     
  4. Mark Fisher

    Mark Fisher Subscriber

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    Thanks to both of you. This is exactly what I needed. I'll try it tomorrow evening!
     
  5. msonelson

    msonelson Member

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    A reader might note that Dr. Rudman's formula calls for concentrated sulphuric acid. If you are using the 48% sulfuric acid solution double the quantity to 13ml.