Red sensitrization

Discussion in 'Silver Gelatin Based Emulsion Making & Coating' started by wildbillbugman, Aug 4, 2010.

  1. wildbillbugman

    wildbillbugman Member

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    Hi PE and All,
    I am finally getting into some serious work on a panchromatic emulsion. I now have a reliable blue sensitive emulsion which contains no gelatin or other plant or animal derivatives. Although I have not determined its ISO yet, it is fast, without being grainy.
    I intend to publish the recipe and procedure on this forum once I am absolutely certain that I can make the same emulsion over and over again.
    As per PE"s recommendations I am using Sands SDE3008(green sensitization) and SDE3057(red sensitization with "J" aggregation in the presence 0f iodine).
    I am using 100mg/M Ag of the SDE3008 and 200MG/M Ag of SDA3057. The double dose of SDA3057 is for the formation of the "J" aggregates. I am adding a small amount of KI to the emulsion 15 minutes prior to addition of the dye.
    Although the emulsion should be cyan in color, it is a light pink. But it is much less pink than the magenta colored emulsion containing SDE3008 (for green sensitization), even though the dye concentration is twice as high.
    AND-a red sensitivity test, via exposing through a #25 filter shows strong red sensitivity.
    Could my pink color of the red sensitive emulsion be due to too much SDA3057 ?
    Should I decrease the dye concentration to 150mg/M Ag?
    Regards,
    Bill
     
  2. Photo Engineer

    Photo Engineer Subscriber

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    Usually, a red color in an emulsion with red sensitivity indicates two things. Some green sensitivity is present and there is too much dye.

    PE
     
  3. wildbillbugman

    wildbillbugman Member

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    Hi PE
    I made another divided batch of emulsion for R;G;& B sensitization. This time I reduced the SDA3057 from 200 to 150mg/M Ag. The emulsion is not bright cyan, but it is a "khaki" green. Probably a step in the right direction. The unsensitized blue sensitive emulsion is very bright yellow. A cyan would have to be very strong indeed to completely mask the yellow.
    Exposing through a #25 again shows strong red sensitivity.
    Bill
     
  4. Photo Engineer

    Photo Engineer Subscriber

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    I think that you might be there. This indicates that you have a coarser grained emulsion than the one I tested. As grain goes up, amount of dye goes down.

    It would be blue of there was some green sensitization, so this is probably ok.

    PE