Re: glutaraldehyde

From: "T. E. Andersen" <postlister@microscopica.com>
Subject: Re: glutaraldehyde
Date: Thu, 18 Mar 2004 11:58:49 +0100

> Judy Seigel wrote:
>
> > My tests also show, by the way, that when your size is TOO hard, you lose
> > highlights because the gum layer tends to roll off. So the "right"
> > treatment CANNOT be decided by a book or theory, ESPECIALLY one geared to
> > silver gelatin emulsion.
>
> More or less my point, too! I do not believe (nor have I said) that
> silver practices can be used to advantage in all other processes!

This is very irrational. You are saying disadvantage of hardening the
gelatin size with too much of "reversible" hardener, and complaining
the loss of highlights because the hardener diffuses out to the gum
layer. With appropriate amount of glutaraldehyde, that problem should
be greatly minimized because less glutaraldehyde is needed, and once
GTA is attached to gelatin (which is fairly rapid), it is much much
less likely to come off and diffuse out to adjacent layer, unlike
formaldehyde.

Chemistry of gelatin and hardener is the same no matter what the
process is. It's just that silver gelatin literature, having
benefited from latest applied sciences, tends to be more technical and
not written in the same language as the ancient literature like some
of the early silver gelatin literatures or alt process literature. But
the latest dichromated colloid processes literature is very detailed
and technical for the same reason. (I'm talking about holography
literature.)

> > Meanwhile, Tom, there are prints that were hardened in formaldehyde that
> > still look pristine after 100 years...
>
> That's in fact exactly my point (and that's why I'm saying that the
> safest thing is to stick with formalin)!

You are judging by looking at some survived samples and disregarding
many samples that are damaged by insufficient hardening and its
consequences such as damaged coated layer in very humid storage
condition.

--
Ryuji Suzuki
"All the truth in the world adds up to one big lie." (Bob Dylan 2000)