Hello to PE and All,
I have compleated my last evaluation of my current batch of panchro emulsion until I have recovered from my upcoming surgery sufficiently to move around and lift things.
My last experiment was to add O.5 M% of formalin to the the emulsion. As I have observed befor, by adding formalin to my type of emulsion, based on silane functional PVA instead of gelatin, the formalin produced two benifits. First, it caused the emulsion to coat more smoothly. The craters I observe without it are greatly reduced. Secondly, fogging is greatly reduced. I have observed the latter time after time with the type of of emulsions I am making. I do not pretend to know the reasons why. But it works. I would bet my left little toe on it. Glyoxal is more tricky. I avoid it since I once crosslinked one of my emulsions immediately upon adding the glyoxal.
When I get back to wet work, there are 2 more things that I need to do befor I begin using this emulsion to produce in camera color seps.-A, I must reduce the alcohol precipitations from 2 to 1. My emulsion,after re-uptake in water, was too thin. So I did a second alcohol precipitation being more careful to press out and drain as much water as I possibly could. The second re-uptake required a higher temperature, giving rise to more foging. 2- I would like to replace SDE 3008 with a cheaper sensitizer. There are many green sensitizers that cost far less than $600/gram+convenience fee.
In late May-June, I will return to this work and eventualy post the formula and procedure here.
Bill