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  1. #1

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    Drag bleaching as per Thornton

    In the late Barry Thornton's book "The Edge of Darkness" he describes a technique he calls Drag bleaching (in the last chapter "revealing irregularities").
    He immerses a fully toned (selenium) print in dilute bleach (NB! not reducer as there is no hypo present). The seleniumtoned silver resist bleaching, but as the selenium toner works from the shadows first, the highlights are least resistant to the bleach. The effect is that the bleach works on the highlights, while leaving the shadow. He warns against leaving the print too long in the bleach, as it will go too far. If it go too far, you can only redevelop as it is bleach and not reducer that has been used.
    Anyway, I get the impression that one actually sees how long the print should be bleached, and then washed and transferred to fix.

    I have tried this. My first observation was that very little happened in the bleach. When transferred to the fix, everything happened in terms of effects from the bleaching.

    Consulting other sources regarding bleach, it turns out thet fix act as a catalyst to the beach, and is necessary to obtain a bleaching effect (but then we are talking about permanent reduction?)

    What am I missing from Thornton's procedure??

  2. #2
    Ian Grant's Avatar
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    The selenium toning is masking what's happening in the re-halogenating bleach, when you bleach the silver slightly it doesn't disappear the silver halide goes a brownish colour, but place in fixer that part suddenly gets dissolved. It's best to keep your test strips & scrap prints,etc to do initial tests with before bleaching the final print.

    Ian

  3. #3
    Nicholas Lindan's Avatar
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    I have tried bleaching Se toned prints in Farmers - which contains fixer - but had no success at all in reducing the highlights. I imagine it depends how thorough the toning is. The inability to bleach might be a good test for complete toning?
    DARKROOM AUTOMATION
    f-Stop Timers - Enlarging Meters
    http://www.darkroomautomation.com/da-main.htm

  4. #4
    Ian Grant's Avatar
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    It probably is also quite varied with different papers too. I found it relatively easy to bleach a heavily toned print on Agfa MCC.

    Ian

  5. #5

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    Thanks for quick replies!
    So if i got this right: there is little to see until after the fix, and the best way is to figure out the bleach time by using teststrips.
    If the bleach-time proves too short, can I re-immerse in bleach after fix (after a short wash?)

    Would it be better to limit the toning by using more dilute bleach and/or shorter time (I use KRST 1:4 for 5 min @ 20 centigrades),
    so the highlights aren't that much toned and less resistant to bleach?

  6. #6
    Ian Grant's Avatar
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    You really need to test the paper you're using. If I used KRST 1:4 for 5 mins @ 20°C for 5 mins my Agfa paper would have split toned, and my current Forte Polywarmtone gone bright Red

    So try a few rough experiments with test strips & scrap prints. Try toning for less also try using more dilute bleach, see what happens.

    Ian



 

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