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  1. #11
    Joe Lipka's Avatar
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    After my first post, I thought, golly, I forgot to mention that the NA2 was diluted from the 20% stock 1 to 7 with distilled water.

    I do use the NA2 but very diluted. Seemed to work well for me.

    In the post about 6-0-3-3-1, are we talking about FO#1, FO#2, NA2, Pt and Pd?
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  2. #12

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    LOL...I was wondering about that, I thought jeeezz..those negs must have a DR of 0.02....

  3. #13
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    Quote Originally Posted by clay
    Bottom line: if you want some platinum in your image, you gotta use another method of contrast control.
    Clay,
    The "NA2" platinum starts as Pt(+4), gets reduced to Pt(+2) consuming ferrous without forming image (that's the contrast control mechanism). Then if there remains enough ferrous in that area of the print, Pt(+2) is further reduced to metalic Pt(0). Some Pt metal is deposited, so the result is a TRUE Pd/Pt print.

    However, it is true that initially adding "normal" Pt(+2) to the sensitizer mix greatly negates the contrast effect of added Pt(+4). Chemically, it's not entierly clear to me why this is, but it most certainly is the case.

    Linas
    Linas Kudzma

  4. #14
    clay's Avatar
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    I did not mean to imply that you wouldn't get platinum in the image, only that if you decide to put regular pt(II) metal salt in your metal component, that it would negate the contrast control effects of the Na2 (PT(IV)), at least according to the information provide by Howard Efner.

    I normally print in pure palladium, so this is a non-issue with me. But I realize a lot of people might normally use say, a 25% pt & 75% pd metal proportion, and that the presence of the pt(II) was problematic in its effect on the contrast control offered by Na2. Like you, I am not entirely clear about the reason.

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