Glutaraldehyde again

From: Katharine Thayer ^lt;>
Date: 06/11/04-09:28:09 AM Z
Message-id: <>

As you all know, I sized a bunch of paper with gelatin and
glutaraldehyde a couple of months ago. As I said at the time, I'm not
sure why I did that, because I bought the glutaraldehyde to harden gum
for my gum-painting project, not to size paper for gum printing. But
whatever my intentions were, there is no doubt whatever that I did size
some paper with gelatin and glutaraldehyde.

I haven't used this sized paper very much because I prefer printing with
unsized paper, and when I tried the paper early on
with some test prints, I didn't like the way it printed in terms of
contrast; eg the Fabriano Uno which prints very dull and flat unsized,
printed just as dull and flat with this sizing/hardening combination.

Recently I've tried the sized paper several times, just because it's
there and I hate to have paper go to waste, and I've found that
with aging the paper has changed its behavior considerably. Now it
starts out developing normally, but after 20 or 25 minutes of looking
like a normally-developing print, just before the details finish
emerging from the shadows,suddenly the image starts to look grainy and
white spots appear in the coating, and within a few minutes the entire
image just disintegrates and flakes off.

I've scanned comparison test prints using the same negative, same paper
(Lana Aquarelle), same coating mix, same everything except in the one
case the paper is unsized and the image prints and develops normally; in
the other case the paper is sized with gelatin and glutaraldehyde and
does like I described above: It developed normally except for having
more contrast than I like in a print, for about 20 minutes, and then it
suddenly started looking very granular and then the image just started
disintegrating. (I grabbed it out of the water just as the image was
beginning to disintegrate, or there would have been nothing to see at
all.) I should add that I consider this to be a different phenomenon
than the kind of flaking that occurs when the coating is too thick or
too pigmented: (1) that kind of flaking, IME, occurs sooner in the
development process; the image starts coming apart almost as soon as it
hits the water, and (2) it just looks different; the granularity is
different from the other kind of flaking.

Then I went ahead and printed on the gelatin-glutaraldehyde-sized Uno as
well, since I have it, but I didn't bother to compare it with a print on
unsized Uno. This print demonstrates the granularity that develops in
the image on glutaraldehyde-hardened gel size, again after about 25
minutes, as well as the attenuated DMax that I've been complaining about
from Uno: this is what I'm talking about.

I mixed this glutaraldehyde at .04% as a proportion of the gelatin
solution; I think I figured out once that Chris mixes hers at .015%, so
it's possible that I used too much of the glutaraldehyde. But this is
just another one of many reasons why I'm not convinced that
glutaraldehyde is the way to go. But since I don't size anyway, this is
just information for those of you who do size to put into your mental
databases for whatever it's worth to you.

Oh, here's the URL:

Katharine Thayer
Received on Fri Jun 11 16:28:05 2004

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