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  1. #1

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    D-512 compensating developer (Silom Horwitz)

    This formula appears in Modern Photographic Processing (Grant Haist) Vol. 1. in the context of low contrast development. The formula is attributed to Silom Horwitz (1967), based on Marilyn Levy's studies of the superadditivity of Phenidone and Pyrogallol.

    Stock solution (1L):

    1g Calgon
    40g Sodium Sulfite
    6g Pyrogallol
    2g Phenidone

    The working solution is a 1+1 dilution of the above stock solution. Development time at 68F was 10min for Kodak Plus-X, rated at ISO speed. It was recommended only for high contrast subjects requiring low contrast development.

    I suspect the Calgon could be eliminated if distilled water is used for mixing/dilution.

    This has been on my list for a while in my ongoing "survey" of purported low gamma and high speed/low gamma developers. I'm curious to try it, although dissolving 2g Phenidone is a pain. Perhaps I'll mix the working solution (halving all amounts) as a one-shot.

    If anyone out there has already tried Horwitz D-512 with any current films I'd be curious to hear about it.

    Michael

  2. #11
    Ian Grant's Avatar
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    No Calgon is has no effect on the alkalinity. It's just there to help if you have hard water.

    Ian

  3. #12

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    Quote Originally Posted by Regular Rod View Post
    Is the Calgon not there to provide an alkali? How long does the stock solution keep for?

    RR
    As Ian said, the Calgon is in there as a sequestering agent, which is why I think it is safe to omit it if using distilled water. The Sodium Sulfite in this formula provides the alkalinity. As for keeping properties, I wouldn't expect it to keep very well without modifications. This is essentially a Phenidone-Sulfite developer - similar to POTA (with Pyro added to stabilize/regenerate the Phenidone) so I would not expect it to have a shelf life. I'm hoping to try it out this weekend (assuming my Pyro is still workable).

  4. #13
    Athiril's Avatar
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    Quote Originally Posted by Michael R 1974 View Post
    Indeed it seems to be a more "stabilized" version of POTA. In Anchell/Troop the addition of Pyro, HQ or Catechol are discussed as potential ways of stabilizing the Phenidone enough (by superadditivity) to make POTA easier to use. Even Metol is considered (not sure why but it seems to follow Crawley's thoughts) and also Glycin - presumably for its apparent ability to make other agents more resistant to oxidation. But the suggested formulas in FDC use small amounts of these additional agents, less sulfite and sometimes additional alkali. D-512 seems quite different in its Pyro concentration.

    On the other hand the formulas in FDC are intended primarily for document/microfilms. D-512 is mentioned in Haist in the context of compensating developers for general purpose films, while POTA is discussed in the context of microfilm development.
    Possibly to prevent the terrible highlights you can get with phenidone alone, or phenidone in high amounts.

  5. #14

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    Phenidone is unstable in solution. It can be stabilized with the addition of another developing agent. The phenidone is regenerated at the expense of the other developing agent.

    The H&W developer was optimized for use with microfilm. A better choice for general purpose use might be Perfection XR-1.
    Last edited by Gerald C Koch; 12-09-2013 at 07:18 PM. Click to view previous post history.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

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