How many variants of D-76?

Discussion in 'B&W: Film, Paper, Chemistry' started by Keith Tapscott., Aug 29, 2005.

  1. Keith Tapscott.

    Keith Tapscott. Member

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    I`ve been looking at formulae of Kodak D-76 and there seems to be quite a lot of them. eg: D-76/ID11, D-76b, D-76d etc.
    How many are there of D-76 out there?
    Even the current MSDS for E.K. D-76 is a little different from the original formula.
     
  2. Gerald Koch

    Gerald Koch Member

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    I have formulas for the following D-76b, Buffered, BB, c, d, F, H, X, and DK-76. In reality there are many fine grain developers that can be considered as variants of D-76. Just about any formula containing only Metol, borax and ~100 g/l of sodium sulfite. At the low pH of D-76 the hydroquinone does not actively participate in the development process but merely regenerates the Metol. Therefore, you may find it missing in some fine grain formulas considered D-76 variants such as D-76H and D-96.
     
  3. Keith Tapscott.

    Keith Tapscott. Member

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    Thanks Gerald, I`m not sure if the D76H and DK-76 that you mention are official Kodak formulas or not. What I was wondering was what their various functions over the standard formula were? I expect that there are many developers of the D-76 type formulated by many other photo-chemical manufacturers too. Gevaert G-206 is close with just one gramme less of Hydroquinone.
     
  4. Gerald Koch

    Gerald Koch Member

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    DK-76 is indeed mentioned in Kodak literature. D-76H was suggested by Grant Haist to avoid the problem of the activity of D-76 increasing with age. This is caused by the oxidation of hydroquinone and the creation of hydroxyl ions which increases the pH. Many of the variants attempt to fix this problem. D-76H simply solves the problem by omitting the hydroquinone and increasing the amount of Metol to 2.5 g/l.

    Some like D-76c are modified for special purposes.
     
  5. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member

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    Ryuji Suzuki, who has been around APUG of late, has written a veritable dissertation on D-76 on his website. A google search should turn it up.
     
  6. eatfrog

    eatfrog Member

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  7. Ryuji

    Ryuji Member

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    Well I shouldn't start joining this thread for there are too many things that can be discussed. But just a few.

    D-76H type developer is fine if you mix the solution immediately before use (say a week or so). But the developer performance goes down faster than D-76 or D-76d, so D-76H is unsuitable for people who premix and store the developer.

    What Jerry Koch said about superadditivity in his previous post is misleading. Hydroquinone in reasonable MQ developers are merely regenerating Metol, not just in D-76. The raised pH is having to do with sulfonation of quinones, which generates hydroxides. It has nothing to do with ionization of hydroxyl groups, which generally behave as an acid.

    There are so many variants of D-76. I think the most novel part of the original D-76 is that the alkaline agent is borax. In most developers of late 1920s, developers used carbonate or hydroxide. At the same time, importance of many of D-76 variants is lost. Today's emulsions are manufactured with more specification/goal-oriented top down design, rather than ad hoc trial-and-error approach which was mainly used until about 1970s. Users don't see enough of difference in resulting image quality from small differences in the developer formula.

    DK-76, with sodium metaborate in place of borax, has little or no advantage over D-76d, in my opinion.

     
  8. dancqu

    dancqu Member

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    D-76H, is a misnomer. D-23+B would be more accurate; D-23
    with a little borax and one third the metol. Subtract the borax
    as well.

    The very little borax in D-76 serves only to restrain an
    increase in ph. Rather than an unrestrained build up of OH
    radicals, the borax hydrates and metaborate is formed. Although
    the ph still increases it does so at a more moderate rate.

    I did subscribe to another explanation for D-76's ph
    instability. As put forth by Milan Merhar some years ago,
    the slow hydrolysis of the borax is the problem. That sounded
    plausible. But then again why included an ingredient
    which had no purpose but to cause problems? I no
    longer subscribe to Merhar's reasoning.

    Some account for the presence of the borax because it
    works as an activator. That can't be because it amounts
    to only 1/50 part of a substance, sodium sulfite, which has
    a ph a little higher than that of itself.

    I think that borax-metaborate ph control a good reason
    for borax being present WHEN hydroquinone is present.

    Subtract the hydroquinone and the borax, triple the metol
    and call it D-76HB XXX or D-23. Dan
     
  9. jnanian

    jnanian Advertiser

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    sprint film developer is a metol free replacement for d76
     
  10. Keith Tapscott.

    Keith Tapscott. Member

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    This all depends if you want a Metol free developer, if you prefer PQ or have an alergy to Metol, then fine. Some people prefer the tonality of films developed in MQ or Metol based developers.
     
  11. jnanian

    jnanian Advertiser

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    keith -

    d-76 and sprint film developer are identical and you will not be able to see the difference between film processed in one or the other.

    http://www.sprintsystems.com/products.html
     
  12. Gerald Koch

    Gerald Koch Member

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    Everyone seems to have settled on the name D-76H, I assume to connect it with Grant Haist who suggested it.

    Merhar's reasoning is faulty, borax does not hydrolyse and is a stable compound. In fact it is used to make pH standard buffers.