Re: Chrome Alum Gelatin hardener

From: wcharmon@wt.net
Subject: Re: Chrome Alum Gelatin hardener
Date: Mon, 09 Feb 2004 19:06:03 -0600

> On a second note, I googled glutaraldehyde, and the first two pages
> were health warnings and MSDS information about possible side
> effects from exposure to this chemical. These effects sounded
> awfully similar to those of formaldehyde. Is there any other
> inherent advantage other than the ones mentioned. (I guess this part
> is directed at Ryuji)

The kind of potential problems and typical symptoms may sound similar,
but glutaraldehyde is much safer than formaldehyde.

In terms of the hardening effects of glutaraldehyde, it is one of the
most preferred aldehyde hardening agents because of practical
hardening effects, even among dialdehyde family. For example,
stability of cross links formed is superior, the range of
concentrations and other conditions in which hardening effect is
obtained, the degree of hardening that can be obtained, effectiveness
as the hardening agent... For example, cross links formed with
formaldehyde or glyoxal are not very stable, and they can be broken
with weak acid or high temperature. Cross links of
glutaraldehyde-hardened gelatin are stable even in dilute acid or at
boiling temperature.

Kate: we talked about this before... too bad you can't find
glutaraldehyde in NZ. Unfortunately, this is the best hardener I've
ever tried, and I can't recommend other compounds from the literature
because I haven't tried them...

By the way, one of my old shoes I wear in darkroom had white stain
when I left darkroom last time. It's black now. I suppose this is a
silver gelatin emulsion printed out on suede leather... Should I tone
this to make it archival?

--
Ryuji Suzuki
"Reality has always had too many heads." (Bob Dylan, Cold Irons Bound, 1997)