Question on Kevin`s Emulsion

Discussion in 'Silver Gelatin Based Emulsion Making & Coating' started by wildbillbugman, Apr 7, 2009.

  1. wildbillbugman

    wildbillbugman Member

    Messages:
    819
    Joined:
    Apr 18, 2005
    Location:
    San Bernardi
    Shooter:
    8x10 Format
    Hi Kevin,
    I took notice of your formula on TLF. I noticed that it contains no I. You call it a "slow" emulsion. But the apeture/shutter speeds which you give are faster than I would expect. Have you ever tried including I in the pre-percipitation phase? I have not tried to make this emulsion yet, and would like to read your response befoe I do.
    Bill
     
  2. kevin klein

    kevin klein Member

    Messages:
    163
    Joined:
    Mar 20, 2006
    Shooter:
    Large Format
    Bill

    I did add iodide to a batch and it had less density for some reason. I do not recall the speed of it but I never added any more iodide. The reason the emulsion is called slow is because most people consider anything less than 25 as slow, at least that is what I think.
     
  3. Photo Engineer

    Photo Engineer Subscriber

    Messages:
    26,262
    Joined:
    Apr 19, 2005
    Location:
    Rochester, NY
    Shooter:
    Multi Format
    Iodide typically increases speed while decreasing the development rate of the emulsion and also slowing down the action of the hypo added to it to sulfur sensitize.

    There are two solutions. The first is to increase the finish level if it is not long enough or hot enough, and the second is to use a longer development time.

    PE