Re: Hardening gelatin (Ws: glutaraldehyde)

From: Katharine Thayer ^lt;>
Date: 04/01/04-02:36:27 AM Z
Message-id: <>

Judy Seigel wrote:
  The unhardened size stained noticeably on the BFK, the
> hardened didn't stain at all. On the Arches, both stained but the
> unhardened stained more.

Interesting how different our observations are, as I found Arches
printed without pigment stain, either unsized or sized with unhardened
gelatin. Which just goes to show how little use our personal
observations are to other gum printers. My advice for gum printers
looking for answers is: Run for your lives! Don't listen to any of us,
just listen to the materials and learn from them. Stop reading this junk
and just go make gum prints; you'll learn all you need to learn from the
doing of it, and what you learn will probably be entirely different from
anything you read here.

The question of whether sizing is necessary, or whether hardening is
necessary, depends on so many things, including the skill of the
printer, that I think an attempt to lay out some kind of law about it
would be foolhardy.

Here's what I think: if you can learn to print without sizing, that's
the best way to go. If you can't, then size. If you size with gelatin,
then the size should probably be hardened one way or another. The
hardening is not to keep the gelatin from melting during gum
development; as Ryuji rightly says, the temperatures we use aren't
likely to melt the gelatin. Instead, the hardening is important because
unhardened gelatin may invite mold, fungus, insects, and thereby
compromise the longevity of the print.

If you find that you can't print without pigment stain on unhardened
gelatin, then of course you need to harden before printing. If not, and
if you are printing images that contain tone throughout the image, and
if you use a fairly strong dichromate solution, then it seems reasonable
to me to assume that the gelatin will be hardened throughout by the
dichromate during printing. If there are large areas of white in the
image, you should either harden the gelatin before printing, or soak the
print in hot water after printing to remove the areas of unhardened
gelatin that weren't hardened during printing due to lack of exposure.

Katharine Thayer
Received on Thu Apr 1 10:32:33 2004

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