Copper Sulfate Bleach

This formula is from Tim Rudman’s ‘The Master Photographer’s Lith Printing Course‘, a book now out of print but readily available secondhand. Many of the materials mentioned in the book are sadly no longer available, but the techniques hold good with the few modern papers remaining.

Copper (Cupric) Sulfate..................................50 g
Concentrated Sulfuric Acid (EXTREME CARE!)..............6.5 ml
Sodium Chloride (Common Salt)........................... 50 g
Water to make..........................................1000 ml

IMPORTANT NOTE: Always add strong acids to water slowly and NOT water to acid.
This formula makes a stock solution that is diluted 1+9 with water for dish use. The stock has a very long shelf life and the diluted working solution will bleach around 3-4 10×12″ prints before exhaustion.

Bleaching should be carried out on a thoroughly fixed and washed print. The use of hypo clearing agent after an initial wash, followed by further washing, is recommended.

Bleaching is initially slow at this 10% dilution, but suddenly proceeds rapidly. Using this dilution enables more control should only partial bleaching be required.

7 Responses to Copper Sulfate Bleach

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  4. Dennis says:

    Hi thanks fornthe recipe, it just says concentrated sulfuric acid, how many percent did you use? Will 20percent be enough? Greetings

  5. Roy Hammans says:

    Hi Dennis, thanks for the enquiry. I used concentrated sulfuric acid, which is around 98%, but that may not be easy to obtain and of course requires VERY careful handling. Using dilute sulfuric at around 20% may work but I would imagine will take longer. Perhaps dilute the stock solution to 1+4 instead of 1+9 and experiment? I’d be interested to hear if you do and will amend this page accordingly.

  6. lab rat says:

    Thank you for this! I’ll have to test it for film reversal. It would be great if it could replace the more toxic options!

    Regarding acid concentration:
    If you have a 20% solution, just adjust the volume, to give the same final concentration: V1 * C1 = V2 * C2. Solved for V2:
    V2 = (V1 * C1)/C2.
    To adjust for 20%: Volume of 20% H2SO4= (6,5ml * 98)/20 = 32ml.

  7. lab rat says:

    Ps. When you say 3-4 10×12″ prints: Is that per liter of diluted solution?

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