Question on Kevin`s Emulsion

[wildbillbugman]

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

 

[kevin klein]

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.

 

[Photo Engineer]

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