Re: PT/PD and humidity redux

From: Ender100@aol.com
Subject: PT/PD and humidity redux
Date: Tue, 02 Mar 2004 00:17:13 -0500 (EST)

> I had an interesting experience the other night$,1rt(Bbut I won't go into that.

Here goes another piece of useless information.

I haven't looked at chemistry of other processes closely, but in
silver gelatin process it's well described in literature that moisture
of the material (as well as other environmental factors like
temperature, oxygen,...) affect photographic speed of the material. I
often notice speed difference when I test emulsion without completely
drying, compared to finished material which I dry for much longer.

If you find retention of humidity in your material advantageous, you
could add a small bit of glycerol to your sensitizer solution. If you
add too much, drying may take much longer time, or may not dry enough,
so start with very small amount. Glycerol will wash out in wet processing.

You could use ethylene glycol, diethylene glycol, triethylene glycol,
propylene glycol, etc. in place of glycerol if less humectant effect
is desired. Kodak PhotoFlo 200 contains some of these.

--
Ryuji Suzuki
"Reality has always had too many heads." (Bob Dylan, Cold Irons Bound, 1997)