Heating Halide and Silver Nitrate sol'n before emulsification

Discussion in 'Silver Gelatin Based Emulsion Making & Coating' started by Kirk Keyes, Nov 10, 2008.

  1. Kirk Keyes

    Kirk Keyes Member

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    I'm wondering about some emulsion formulas and patents that have the halide and/or silver nitrate solutions warmed up to about the same temp as the emulsion kettle. So instead of having these solutions at room temp, they are warmed up.

    Is this to have the solution already at working temp so that more silver ions stay in solution instead of precipitating because they are cold and then they possibly redissolve as the grains warm up as they mix into the warmer solution?
     
  2. dwross

    dwross Subscriber

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    Kirk,

    It's my impression from the literature and from watching my own cauldrons, that having the silver solutions at the same temp as the gelatin + halide is a way to increase consistency and repeatability. Temperature at precipitation is crucial to grain size, as is the total ripening time. Adding the silver at the same temp is an easy and low-tech way to assure your real time of cooking is a constant. For all I know, there are other things going on, but consistency is the big deal here.

    Denise