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  1. #11

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    Quote Originally Posted by avandesande
    hydroquinone only has two phenolic sites on it vs 3. hydroquinone does not crosslink with the gelatine as readily as pyrogallol or pyrocatechol. Crosslinking is what chemically binds the pyrogallol to the gelatine causing stain.
    Hydroquinone (1,4-Dihydroxybenzene);
    Catechol (1,2-Dihydroxybenzene);
    Pyrogallol (1,2,3-Trihydroybenzene).

    All three of these Benzine Ring compounds have the potential to act as tanning and staining developers. Sulfites can depress or stop the tanning and staining with all three.

    Pyrogallol is the most active of the three. Catechol is less active than Pyrogallol and more active than Hydroquinone. In general, it is possible to substitute one of these reagents for another, taking into account the differences in activity.

    All three developers become more active in the presence of sulfite - but with addition of too much sulfite lose their ability to stain and tan.

    All three developers are additive (show increased activity) or are superadditive with phenidone and phenidone derivatives.

    All three developers are additive with Metol.

    All three developers are additive (or superadditive) with ascorbic acid.
    Tom Hoskinson
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  2. #12

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    It is probably a difference in activity (proportional stain) between pyrogallol and HQ of at least a factor of 4 if not more. So yes, technically it stains but not in a useful sense.
    Any of these developer solutions will turn colors and fog the negative. This in not what people are looking for.

  3. #13

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    Gainer's staining developer gets good reviews from other people. I tried it and did not see a lot of fog. I bleached it out to see the stain. It did not appear very strong, but I haven't tried any pyrogallol or catechol developers.

  4. #14
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    Quote Originally Posted by psvensson
    Gainer's staining developer gets good reviews from other people. I tried it and did not see a lot of fog. I bleached it out to see the stain. It did not appear very strong, but I haven't tried any pyrogallol or catechol developers.
    I haven't tried the Gainer formula (yet) but one thing I have noticed is that fog level is visually higher with the HQ developer than what I get with developing in say Rodinal. What can be done to reduce fog level? Addition of KBr?
    Last edited by Canuck; 06-06-2005 at 05:05 PM. Click to view previous post history.

  5. #15

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    Gainer's developer uses TEA rather than carbonate as the activator, so it has a lower pH that may mean less fog. Metaborate could also work.

  6. #16

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    Quote Originally Posted by avandesande
    It is probably a difference in activity (proportional stain) between pyrogallol and HQ of at least a factor of 4 if not more. So yes, technically it stains but not in a useful sense.
    Any of these developer solutions will turn colors and fog the negative. This in not what people are looking for.
    In my direct experience, Hydroquinone based staining and tanning developers produce useful stain and proportional tanning with low fog.
    Tom Hoskinson
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  7. #17
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    Quote Originally Posted by psvensson
    Gainer's developer uses TEA rather than carbonate as the activator, so it has a lower pH that may mean less fog. Metaborate could also work.
    Next experiment I'll try borax. Since borax is less basic, does that mean my development times needs to be increased?

  8. #18

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    Hi,

    I am using since long time, the formula below and the result is what I expect from that kind of developer. The only reason why I am using hydroquinone instead of catechol is very simple because it is difficult if not impossible to have catechol in Turkey.
    The keeping properties are excellent, and I think that it is worth to give a try.

    Here is the formulae.

    Best
    Mehmet Kismet

    A:
    Distilled water : 400cc
    Sodium Bisülfite 5g
    Hydroquinone 25g
    Phenidone 1g
    (dissolved in5cc
    isopropyl alcohol)
    Pot. Bromide 1g
    Water to make 500cc

    B
    Distilled water 1000cc
    Sod. Carbonate 200g
    (anhydre)

    Some data for 4"x5" FP4(EI 64) with JOBO CPP-2 and 3010 drums with rotating speed @P
    (N)
    10A + 50B + 750Water
    8min.@22oC

    (N+2)
    15A + 75B + 750Water
    6,5min. @22oC

  9. #19

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    Quote Originally Posted by Canuck
    Next experiment I'll try borax. Since borax is less basic, does that mean my development times needs to be increased?
    You're going to need a lot of borax to get your times close to what you get with carbonate. I wouldn't go there.

  10. #20
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    Quote Originally Posted by psvensson
    You're going to need a lot of borax to get your times close to what you get with carbonate. I wouldn't go there.
    Hmmm ... more time in the darkroom and this is bad how?

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