Re: glyoxal yellowing

From: "Christina Z. Anderson" <zphoto@bellsouth.net>
Subject: Re: glyoxal yellowing
Date: Thu, 03 Feb 2005 10:03:20 -0500

> Kees, the Maco hardener---very interesting! Is the percentage of
> glut in it really 2.5-5%? If so, then 50 ml of this is a lot more
> than my 6 ml. per liter of gelatin.

If I read correctly, I think Kees immersed plain gelatin sized paper
in dilute glut bath. This is different from what you do, AFAIK. I
personally don't want to do more work than necessary, and sizing,
hardening and rinsing in 3 separate sessions is out of question, where
one is enough.

But when glut is directly added to the sizing solution, the optimal
amount of glut depends strongly on the kind of gelatin and the
concentration of the gelatin. The figure (6ml) is what I used for
gelatin emulsion with high gelatin concentration at that time, and so
it's probably at a very end with 3% food gelatin. You can add more if
greater hardening is desired. (Just test the ratio in a small batch
ahead of time because adding too much glut will ruin the whole batch
of sizing solution and you can't reverse it by adding more gelatin and
water.)

> BUT, if this is truly a 2.5-5% glut, then a consumer would be able
> to buy glut over the counter in small quantities and that is a great
> thing!

I agree!

Glut was also used in E4 processing, I think.

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