Re: dichromated colloids

From: Sandy King <sanking@clemson.edu>
Subject: Re: dichromated colloids
Date: Fri, 21 May 2004 10:54:14 -0400

> I don't find any of of this relevant to the issue of making carbon
> prints. I have used over the years more than a dozen different
> gelatins from many suppliers,including both porcine and ossein
> sources, and they all gave good results in carbon printing. Whether
> the concentration of nitrogen makes any difference I don't know but I
> would not put stock in any reports that show that it does unless the
> tests were actually made in conjunction with making real carbon
> prints.

I don't think impurity issue or exact chemical composition of gelatin
matters much outside of silver gelatin process. In silver gelatin,
some impurities in very small quantity can have a great degree of
influence in the photographic properties of the resulting emulsion
because they have influence in the way photoelectron makes latent
image, for example. Some trace impurities can change grain size even
if all else is the same. Small difference in latent image can cause
big difference, because development process in silver gelatin process
is an amplification with a factor of several billions. So, naturally,
a lot of gelatin research was done by photographic industry, and a lot
of quoted statements come from that area. We know that, and it's not a
problem, until someone who quotes a part of it without appreciating
the whole context.

--
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)