Re: Gum: Supersize it

From: Joe Smigiel <jsmigiel@kvcc.edu>
Subject: Gum: Supersize it
Date: Tue, 21 Dec 2004 20:21:59 -0500

> My guess is that the sky area received the equivalent
> of a tanning exposure like the unpigmented sizing layer might produce
> and that the hot soak removed the original gelatin size from the border
> area previously masked during the yellow exposure.

> The original size I added to these papers was 260 bloom gelatin hardened
> in an aluminum sulfate bath. This size prevents staining with my normal
> exposure and processing procedures.

Well hardened gelatin does not dissolve in boiling water. It also has
very good adhesion on glass, Yupo and paper.

Also, aluminum sulfate is not a very efficient hardening agent,
especially if the pH is not controlled. Did you control the pH?

Also, dichromate diffused from your gum layer to the sizing layer can
give the gelatin size an additional hardening effect if the area is
exposed. Chromium (III) is a more effective hardening agent than
aluminum ion.

So, what you described naturally leads to a question what happens if
you increase the degree of hardening to the gelatin sizing layer.

--
Ryuji Suzuki
"People seldom do what they believe in.  They do what is convenient,
then repent." (Bob Dylan, Brownsville Girl, 1986)