Ultrasonic treatment in emulsion making?

Discussion in 'Silver Gelatin Based Emulsion Making & Coating' started by analogsnob, Dec 2, 2008.

  1. analogsnob

    analogsnob Member

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    I have come accross a reference in Zelikman's "Making and Coating Photographic Emulsions" that discusses the use of ultrasonics to agitate emulsions in the various phases of the emulsion making process. Amoung the stated benifits are the prevention of coagulation of the solid phase; the prevention of the transformation of sensitivity centers to fog centers and the ability to use more sensitization dye and achieve 25% of dye adsorbing to the crystal as opposed to 15% by other methods.

    I know small ultrasonic units are available for cleaning purposes.

    PE your comments?
     
  2. Photo Engineer

    Photo Engineer Subscriber

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    Ultrasonics were never used at EK to make emulsions AFAIK. They were used all of the time to debubble emulsions just prior to coating. That is all I can say really.

    You do have to be careful as you can injure the crystal depending on shape, size, frequency and energy input.

    PE
     
  3. AgX

    AgX Member

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    I guess one idea was to induce lattice defects (most probably in the precipitation stage).

    It is also reported that Glafkides discussed the use of ultrasound.

    But samewhat later, in the early seventies, I.A. Kortnev in the USSR reported beneficial effects.