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  1. #21
    Ole
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    Quote Originally Posted by Tom Hoskinson
    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.
    ...
    One of the really interesting things about these developers is that 1,3-Dihydroxybenzene - isn't. A developer, that is. Utterly useless for all developing purposes.
    -- Ole Tjugen, Luddite Elitist
    Norway

  2. #22

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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.
    You're in a hurry. Mr. Canuck wishes to go where no man
    has gone before then return and tell us of his findings.

    I will suggest he give a bicarbonate-carbonate blend a try;
    perhaps a 50/50 blend by weight for starters. Dan

  3. #23
    NER
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    Hydroquinone is not a staining developer. It exerts a tanning effect, and has been reported to tan (crosslink) more efficiently than pyrogallol or pyrocatechin [A. & L. Lumiere, B.J. Phot., 285 (1906), and A. G. Tull, J. Phot. Sci. 11 (1963)]. Hydroquionone has less reducing power than pyrogallol because of differences in physico-chemical properties, e.g., redox and bromide potentials. See John & Field, "Photographic Chemistry," 1963, and G. Haist, "Modern Photographic Processing," 1979.

  4. #24

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    Sorry, NER but you are wrong. Hydroquinine (1,4-Dihydroxybenzene) is a staining developer and has been documented as such by many researchers - Including Grant Haist.

    In addition, I have a substantial amount of sensitometric data of my own that confirms this.
    Tom Hoskinson
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  5. #25
    NER
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    Give me a citation - or publish.

  6. #26
    NER
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    A citation ... ??

  7. #27

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    Quote Originally Posted by NER
    A citation ... ??
    If you don't trust any of the excellent people on the board who report getting a stain with hydroquinone, try it yourself. It's very easy and the stain is obvious if you bleach out the silver.

  8. #28

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    The stain effects are are also easily quantifiable with a color densitometer. I have previously published the D Log E comparisons (visual channel vs blue channel).
    Tom Hoskinson
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    Everything is analog - even digital :D

  9. #29

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    Quote Originally Posted by psvensson
    ... the excellent people on the board who report getting
    a stain with hydroquinone, try it yourself. It's very easy
    and the stain is obvious if you bleach out the silver.
    " ... report getting a stain with hydroquinone, ... " on film.
    I'd think the very similar character of paper emulsions would
    also serve to demonstrate.

    I remind myself now and then when testing a paper-developer
    combination that paper has in effect a slow speed film emulsion.
    I've only a loose connection in mind at present twixt a papers
    response and expected performance with film.

    To quantify or calibrate I'd have to now and then shoot a roll
    of film then process. Less of a job for a sheet film user. Dan

  10. #30

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    Quote Originally Posted by Tom Hoskinson
    The stain effects are are also easily quantifiable with a color densitometer. I have previously published the D Log E comparisons (visual channel vs blue channel).
    Just to back up what Tom and Jay have stated hydroquinone is definitely a staining developer in the right formula with low sulphite.

    Sandy

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