Re: Gelatin hardening question

From: "Christina Z. Anderson" <zphoto@uslink.net>
Subject: Re: Gelatin hardening question
Date: Sat, 17 Jul 2004 00:27:01 -0500

> The first mention I have of a problem with chrome alum, aside from
> graininess or shrinking paper, is Crawford in 1979. Then a number
> of other authors ditto this: Scopick, Arnow, Reeves, James, etc.

How much of chrome alum do they use? I don't have much experience with
chrome alum hardening (if glut works so well, why bother?) but in
early silver gelatin literature it is commonly suggested that chrome
alum is to be used in quantity less than 1% of the gelatin
weight. Many use less than 1%.

I suspect that those who have problems are using much more of chrome
alum and those molecules that are not bound to gelatin, or those in
excess to obtain desirable degree of hardening at completion are
causing the problems. Gelatin hardening with chrome alum at 1% of
gelatin weight is pretty slow, even at the optimal pH of 6.

--
Ryuji Suzuki
"You have to realize that junk is not the problem in and of itself.
Junk is the symptom, not the problem."
(Bob Dylan 1971; source: No Direction Home by Robert Shelton)