Re: glyoxal yellowing

From: Kees Brandenburg <ctb@zeelandnet.nl>
Subject: Re: glyoxal yellowing
Date: Thu, 03 Feb 2005 20:02:50 +0100 (CET)

> When mixing the hardening agent with the gelatin it doesn't keep.

I always keep the gelatin solution separate and add hardener
immediately before coating. That is, I take about 50ml of sizing
solution in a dish and mix in the hardener. Coat a sheet, and mix
another one. It takes 10 seconds to mix.

If the gelatin solidifies too fast to a stiff jelly that can't be
melted by heating, that's way too much glut. If you can't coat the
hardened gelatin smoothly, I suspect that your coating surface is too
cold.

> For gum printing the gelatin has to be hard enough to resist the
  abrasion from the coating,soaking, streching and drying.

In silver gelatin sizing has to be very hard because coating of the
emulsion is done at 35C or higher.

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