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  1. #21

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    Quote Originally Posted by CBG View Post
    Interesting. I found this comparison of chemicals used as wash aid:

    Solution........................pH at M/250...............Effectiveness relative
    .................................................. ....................to pure water

    Demineralized water...............~6............................ ...1.0
    Sodium chloride.....................6.1.................. ........ .....1.5
    Sodium bisulfite.....................4.1................. ..............2.8
    Sodium sulfate.......................6.4................. ..............14
    Sodium bicarbonate................8.4.................... ............49
    Sodium sulfite........................9.2................ ....... ........87
    Sodium hydroxide...................11.6.................. ............89

    C
    I don't see any carbonate. Just what is meant by effectiveness?
    Were equal molar quantities used? Times and temperatures.?
    Not knowing the test parameters what are we to make of
    those numbers? Dan

  2. #22

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    It came from Haist, quoting other Kodak researchers

    Quote Originally Posted by CBG View Post
    Interesting. I found this comparison of chemicals used as wash aid:

    Solution........................pH at M/250...............Effectiveness relative
    .................................................. ....................to pure water

    Demineralized water...............~6............................ ...1.0
    Sodium chloride.....................6.1.................. ........ .....1.5
    Sodium bisulfite.....................4.1................. ..............2.8
    Sodium sulfate.......................6.4................. ..............14
    Sodium bicarbonate................8.4.................... ............49
    Sodium sulfite........................9.2................ ....... ........87
    Sodium hydroxide...................11.6.................. ............89

    I don't remember where I dug it up, but your information seems like it fits.

    C
    It came from Haist, quoting other Kodak researchers.

    The one common salt not listed which I think would be of "great" interest is sodium carbonate. I presume it would rate up there close to the hydroxide.

    IIRC, Kodak HCA is sodium sulfite plus sodium bisulfite or some other acidic salt. I presume to lessen the swelling of the gelatin, which will give faster results.

  3. #23
    CBG
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    Quote Originally Posted by dancqu View Post
    I don't see any carbonate. Just what is meant by effectiveness? Were equal molar quantities used? Times and temperatures.?
    Not knowing the test parameters what are we to make of those numbers? Dan
    I can't be more informative. Wish I had access to original text in full. I take it that those chemicals help wash paper in rough proportion to the "effectiveness numbers", but that said, I'm sticking with sulfite.

    C

  4. #24

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    Quote Originally Posted by CBG View Post
    I can't be more informative. Wish I had access to original
    text in full. I take it that those chemicals help wash paper
    in rough proportion to the "effectiveness numbers", but
    that said, I'm sticking with sulfite. C
    I see the ph was measured at a concentration of 1/250
    molar. It would be a generalization to say those ph values
    hold at higher or lower concentrations. I'd need to run some
    numbers but can say now that M/250 is very little chemistry.
    Unrealistically little; less than one gram/liter of any of the
    chemicals listed. Hard to believe. Explanation?

    And effectiveness? How so; maybe half the water or half
    the time? Maybe half the remaining hypo using the
    same wash procedure?

    All in all, just some more information that leaves us
    hanging; RE the discussion concerning hypo testing.
    I've more to add to that thread. Dan

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