lith bleach formulas and some experiments

Discussion in 'B&W: Film, Paper, Chemistry' started by Mark Fisher, Jan 6, 2013.

  1. Mark Fisher

    Mark Fisher Subscriber

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    I was doing some experiments over the weekend to dry to reduce the warm tone in some lith prints. I bleached them back in CuSO4/sulfuric acid bleach and found that when I redeveloped in lith, it came up nearly immediately and the tones were much closer to neutral.....like a warmtone conventional print. That made me think about the effect of the rehalogenating agent in the bleach. Most call for Potassium bromide, but can NaCl also be used as a direct substitute? I'd think the resulting redeveloped prints would be a bit warmer than they might otherwise. I'll give it a try in a few days if no one speaks up.

    Thanks -- Mark
     
  2. grahamp

    grahamp Subscriber

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    I can't answer to what will happen on a lith-treated print, but I do have a reference to a Sodium Chloride/Potassium Ferricyanide bleach as giving warmer tones. This is for sepia toning, nominally. 6.6g Sodium Chloride to 35g Potassium Ferricyanide made up to 1l.


    (Creative Elements, Ephraums E., Amphoto 1993)
     
  3. Mark Fisher

    Mark Fisher Subscriber

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    That seems to make sense to me......definitely worth a try. Why use expensive KBr when I can use table salt!
     
  4. Rudeofus

    Rudeofus Subscriber

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    Note that 30 g/l Sodium Chloride are supposedly used in Microdol X as silver solvent! While AgCl is poorly soluble (but still a lot more soluble than AgBr or AgI), there are quite soluble Silver Chloride complexes which will become more of an issue as you increase Chloride level.