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  1. #41
    Photo Engineer's Avatar
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    Most of the emulsion formulas from before 1940 are very primitive and involve some rather tricky steps. Recent ones published in patents are quite different and just as difficult but in a different fashion. For a good example of a modern emulsion see US Patent 6,524,782. This is a modern t-grain make.

    Even if the average person could make a good emulsion, coating it well for in camera or paper printing use would be difficult. Finding the right film support or paper support would also be difficult, as you must have the right substrate to coat on or you get poor adhesion or desensitization. Anyone out there know how to get plain baryta paper with no emulsion on it?

    Another sensitzing dye sometimes used in the 40s and still available is Erythrosin, or tetra iodo eosin. This was reported in early work by Eastman Kodak and other companies as a good ortho sensitizing dye. It is still available and is not overly expensive when you consider the amount needed to sensitize an emulsion.

    PE

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  3. #43

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    If you find something you want look it up at the sigma/aldrich site. It will give you a rough idea on pricing

    http://www.sigmaaldrich.com/catalog/...ncedSearchPage

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    Now that is more like it, the book can be had used for a great discount....Thanks Aaron!

  6. #46
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    Quote Originally Posted by Photo Engineer
    Anyone out there know how to get plain baryta paper with no emulsion on it?


    PE
    According to Christian Nze, Bergger sells plain baryta paper with no emulsion.

    Good luck,

    Don Bryant

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    Hurry up and order one. I couldn't help myself.
    Quote Originally Posted by Jorge
    Now that is more like it, the book can be had used for a great discount....Thanks Aaron!

  8. #48
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    Quote Originally Posted by avandesande
    Thanks for the quick reply, however I should have noted that the transparent support for coating must be subbed or the gelatin will not spread or adhere. Only a few companies do this. Jim Browning has published one source for that type of support, but it is only available in large rolls.

    The same is true for RC paper support. It must have a titanox layer, resin and then a subbing layer for adhesion.

    The baryta from Bergger will be usable, if available. I hope I can get it in less than master rolls.

    PE

  9. #49

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    What does 'subbed' mean (as far as acetate film is concerned)?

  10. #50

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    Similar to this....??

    The polymers per se disclosed in U.S. Pat. No. 3,501,301 are particularly preferred for operation in accordance with this invention. The most preferred polymers for use as a subbing layer in accordance with this invention are a terpolymer of vinylidene chloride, acrylonitrile, and acrylic acid and a copolymer of vinylidene chloride and acrylonitrile.

    It is a requirement in accordance with this invention in order to solve the problem of blisters, outlined above, that the subbing layer be applied from an organic solvent solution. Any suitable solvent for applying the subbing layer to the substrate may be employed such as, for example, dichloromethane, ethyl acetate, methyl ethyl ketone, trichloromethane, carbon tetrachloride, ethylene chloride, trichloroethane, toluene, xylene, cyclohexanone, 2-nitropropane, and the like. Dialkyl ketones, for example, acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl isopropyl ketone and the like are preferred. Methyl ethyl ketone is most preferred. Alcohols such as methanol, ethanol, propanol, butanol, isopropanol, and the like may be used in mixture with the above-mentioned solvents. In applying the subbing layer to the substrate, the ratio of polymer to solvent is not critical; however, the polymer to solvent ratio employed is preferably from about 0.1 to about 10 percent by weight. The subbing is then dried to remove the solvent and the antistat layer is next applied to the subbed film support.

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