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  1. #1
    Ian Leake's Avatar
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    Super-saturated Pt/Pd coatings

    Has anyone made pt/pd prints with super-saturated coatings?

    I'm wondering whether to experiment with these but would prefer to first hear a bit more about their pros and cons.

    Thanks in advance.

    Ian.

  2. #2
    Klainmeister's Avatar
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    Not sure what you mean here, but I do know that the more pt/pd in the solution, the lower the contrast and better chance of fogging.
    K.S. Klain

  3. #3
    Ian Leake's Avatar
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    Quote Originally Posted by Klainmeister View Post
    Not sure what you mean here, but I do know that the more pt/pd in the solution, the lower the contrast and better chance of fogging.
    Thanks. To clarify, super-saturated solutions are heated to high temperatures so that a greater load of iron and platinum/palladium can be deposited on the paper without increasing the water content of the coating. Sort of like double-coating but without the hassle of multiple applications. Intuitively this should increase the Dmax because there is greater density of platinum/palladium in the shadows. But as I said, I've not tried it so I'm hoping to find someone who has.

  4. #4
    eclarke's Avatar
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    Could be interesting. Sounds like time to try some 4x5 contact prints. How high does it need to be heated, do you think?

  5. #5
    Ian Leake's Avatar
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    Quote Originally Posted by eclarke View Post
    Could be interesting. Sounds like time to try some 4x5 contact prints. How high does it need to be heated, do you think?
    The simple answer is, "I have no idea". The thought experiment is straightforward though. B&S quote their Potassium Chloroplatinite as being a 20% solution, and this is fully dissolved at room temperature. By mixing Potassium Chloroplatinite powder into very hot water it should be possible to dissolve more than 20% w/v. I don't know how hot "very hot" is nor do I know how much more "more than 20%" is. The same approach should work for the other solutions in the mix.

    The challenge I foresee is keeping everything hot enough to avoid crystallisation during coating, exposure and development. And of course the benefits, if any, could be outweighed by the difficulty and cost.

  6. #6
    Klainmeister's Avatar
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    Intuitively is right, but in practice you will find it fogs and does not increase DMAX. This is because with the higher concentration of metal, it begins to reflect back light no matter the exposure, thus creating a base fog that has a slight shiny appearance, less contrast, and quite the drain on the wallet. I've seen this numerous times at B+S. If you want increased DMAX that is very apparent and real, try some fumed silica.
    K.S. Klain

  7. #7
    Ian Leake's Avatar
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    Quote Originally Posted by Klainmeister View Post
    Intuitively is right, but in practice you will find it fogs and does not increase DMAX. This is because with the higher concentration of metal, it begins to reflect back light no matter the exposure, thus creating a base fog that has a slight shiny appearance, less contrast, and quite the drain on the wallet. I've seen this numerous times at B+S. If you want increased DMAX that is very apparent and real, try some fumed silica.
    Thanks - I guess that you've saved me a lot of hassle :-)

  8. #8
    Klainmeister's Avatar
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    Just trying to save you some money and frustration! Go ahead and experiment, but I also found this to be true when doing kallitypes, etc. Our theory is that more = less.

    http://www.apug.org/forums/forum216/...atinotype.html

    There's a write up on fumed silica. Using it in it's dry form makes it super easy to roll on and it has a dramatic effect on DMAX that makes PT/PD printers consider reprinting their entire portfolio!
    K.S. Klain

  9. #9
    TheFlyingCamera's Avatar
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    I've had much better luck applying the fumed silica wet rather than dry. I even went so far as to buy a cheap blender to mix it. But otherwise, my experience with it is on a par with what Mr. Klain says - it produces a notable boost to Dmax and overall contrast increase. And applying it wet doesn't add THAT much time to the coating process. I find it dries to a coatable surface within minutes.

  10. #10
    Ian Leake's Avatar
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    Thanks both. This has been another thing on my list of things to try. I really must get on with it soon. Out of interest, is it archival?

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