Re: Help with what I believe is a hardening issue

From: Kate M <kateb@paradise.net.nz>
Subject: RE: Help with what I believe is a hardening issue
Date: Thu, 11 Nov 2004 17:47:07 +1300

> Gelatine is very sensitive to high temperatures - this will destroy its
> "gelling" ability. I kow this from cooking, not science, so I haven't
> got a clue why - think it destroys the protein chains (?). So heating up
> your gelatine until its really hot is NOT good! It's probably shrinking
> up while drying and flaking off the paper, causing the speckles. I use a
> water bath of about 50deg C to reliquefy.

It's true that heating changes rheological properties of gelatin, but
for brief heating to temperature that doesn't cause the gelatin
solution to bubble is ok. I make some of my emulsions at 70C (most are
at 50C) and the solution is kept at these temp up to 2.5 hours. They
still set to gel and respond to hardeners very well.

> I also keep unused gelatine solution in the fridge. You will know if
> it is really off - it smells like a dead animal!

Gelatin size solution will last much much much longer without any of
that problem if you add a small bit of bactericide such as sodium salt
of 2-phenylphenol, which Bayer sells as "Preventol ON extra."

--
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)