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  1. #11

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    Another sodium sulfite question

    Should the amount of developing agent and the amount of sodium sulfite be proportionate? That is, if you increase the amount of developing agent in the developer solution, should the amount of sodium sulfite be increased accordingly??

  2. #12
    gainer's Avatar
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    The acetone plus the sulfite create a high pH. This efect is used in lithographic developers. There's more to it than the high pH in lithography of course.
    You can find my article at www.unblinkingeye.com on some simple developers containing no sulfite that can be mixed from the solids in a matter of minutes and that I have found to be quite good. Look for "Non-Chromogenic Antiscorbutic Developers for Black & White Film."
    Gadget Gainer

  3. #13

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    acetone--it's not just for breakfast anymore

    I read on another website of a film developer using Dektol diluted 1:7 or 1:8 to which an ounce of actione was added. The writer stated: "the acetone dissociated the sodium ions from their usual companions and produced a concentration of sodium hydroxide." That would give a pH of about 12. Would the acetone serve to isolate the developer products?

  4. #14

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    Quote Originally Posted by gainer View Post
    There's more to it than the high pH in lithography of course.
    Contrary to the usual notion that a high ph is needed for a
    lith developer I have produced prints using a 50-50 blend of
    bicarbonate and carbonate. Hydroquinone's first oxidation by
    product upon the reduction of a silver salt is a Very strong
    reducing agent. That by product is responsible for the
    rapid infectious lith development we see take place
    after a print has been in the developer
    for a few minutes.

    I made a few tests at lower than a carbonate's ph. A more
    lengthy initial phase followed by a not so rapid approach to
    the snatch point were the results. Not surprising. Metaborate
    should do. Carbonate is the most logical choice. Likely all
    would agree that lith prints take enough time whatever
    the activator. Dan

  5. #15
    gainer's Avatar
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    When I said lithography, I meant pure black and pure white as in making half-tone screens, line drawings, etc. Most of the lith art prints I have seen have come from more or less normal negatives through high contrast paper and developers. Certainly carbonate or metaborate can produce high contrast. The acetone IIRC depends on the reduction product for a sort of catalytic effect that accelerates developing. I might be mistaken. There is a first time for everything.
    Gadget Gainer

  6. #16

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    Quote Originally Posted by gainer View Post
    The acetone IIRC depends on the reduction product
    for a sort of catalytic effect that accelerates developing.
    Acetone is a substitute for formaldehyde. Perhaps not much
    used as a component in lith developers because of it's being
    flammable. Also the amount needed is much more.

    There are quite a few lith formulas which do not use
    formaldehyde or any substitute. Dan

  7. #17
    David A. Goldfarb's Avatar
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    In general, I would say a metol-only developer is going to be too soft, if you want negs that will print well from normal lighting conditions on Azo grade 2. If the acetone formula increases the contrast, though, then it's a possibility.
    flickr--http://www.flickr.com/photos/davidagoldfarb/
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  8. #18
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    One of the potential side effects of acetone is the fact that it can react gradually with metol consuming both in a condensation reaction. I'll have to look that one up, but I seem to remember it as being possible.

    PE

  9. #19

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    In metric units by my calculation the Paul Bishop formula is:
    Water....................965.5 ml
    Acetone...................34.5 ml
    Sodium sulfite...........2.24gm
    Metol......................1.5 gm
    Apart from the acetone this is similar to the Kodak high definition developer:
    http://www.apug.org/forums/forum233/...developer.html
    The oxidation product of metol is not a developer (Mees&James 3rd Ed p367) so there will be no infectious development.Assuming the acetone complexes the sulfite, its not known what is the free sulfite concentration in the solution.Presumeably it must be enough to remove the metol oxidation product or the developer would not work.Also it may be the acetone produces an amount of sodium hydroxide, I could find no data on this either.
    Last edited by Alan Johnson; 03-10-2008 at 03:27 PM. Click to view previous post history. Reason: Calculation error

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