potassium iodide

John Klayer · Post by **John Klayer** » Mon Sep 16, 2013 11:36 am

Have any of you tried color shifting with a potassium iodide solution? If so, any advice you can give?

Thanks

Martin · Post by **Martin** » Tue Sep 17, 2013 1:51 am

John Klayer wrote:Have any of you tried color shifting with a potassium iodide solution? If so, any advice you can give?

Thanks

If I remember correctly, I used to put the AgX emulsions (Agfa and Ilford materials back then) into a 10g/L potassium iodide solution for one minute or so. That's supposed to convert most of the AgBr to AgI. In order to remove the yellow stain I cleared the plates in a 1% ascorbate solution.

Keep in mind that:
- this process increases grain size and hence leads to enhanced scatter (maybe not much of an issue with the ultra-fine grain emulsions available now though);
- potassium iodide acts as a solvent for AgBr. So dealing with the above mentioned emulsions the KI concentration/insertion time may have to be adapted;
- the wavelength shift introduced by the conversion to AgI is not that large, maybe 20-40nm only.