Re: Gelatin hardening question

Ryuji,
    All different measures (lots in grains and drachms so I'm too lazy to
figure it out right now) but it looks like about 1-3% at most, but in
relation to the gelatin that is a different story. 5% gelatin with 1% or 2%
chrome alum, or like one formula: 1 oz gelatin in 10 oz water mixed with 10
oz water of 1% alum, which would make the alum 0.5% of the whole mix and the
gelatin 5% of the whole mix, or a relation between the two of 1 to 10. I
think this is what you are asking...but I've only had one cup of coffee and
am still groggy.
Chris
> 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
Received on Sat Jul 17 09:10:39 2004