Re: Nonvolatile gelatin hardener

From: mmatusz@pdq.net
Subject: Re: Nonvolatile gelatin hardener
Date: Tue, 02 Aug 2005 09:15:31 -0500 (CDT)

> Looks like something interesting. Thanks for detailed posting of the
> procedure. How would you compare the properties of gelatine hardened by
> epox with traditional chrome alum hardening.

I don't use chrome alum routinely so I did not even consider
comparison against it. But chrome alum is a tricky hardener. If you
use too much and you'll get very viscous solution and sized paper that
doesn't swell enough. If you use too little and the hardening is
ineffective. With epox you can use a bit too much of epox and none of
these problem will occur.

One advantage of glut that Chris Z frequently mentioned is that the
gelatin is hardened but can swell just enough on paper. Epox hardened
gelatin swelled just as much as glut hardened gelatin.

Another advantage of epox is that it can harden by both carboxyl
groups as well as amino groups. Thus epox can harden plain normal
gelatin in a relatively wide range of pH. Chrome alum is quite pH
sensitive and has rather narrow window of effective pH (though it's
not an issue for most plain sizing applications).

For plain gelatin sizing used in well ventilated area, I would prefer
glut because it works very fast, also in a wide range of pH. But if I
know I won't use sized paper for a week, I prefer epox for the
convenience and ease of use. I've also made a few sheets with a
combination of epox and glut but I haven't tested them.
Received on Fri Aug 5 12:25:01 2005