Re: Gelatin hardening question

Ray,
     I don't endorse anything--just happened to have positive results with
glut with two large batches of paper, and plan to use it again, with
caution, and outside, after Katharine's experience. However, I am only
using 2.5% solution, and 3 ml of it per 1000 ml of gelatin.
     What may be helpful, though, is a **comparison** of the toxic effects
of all four--chrome alum, formaldehyde, glyoxal, and glutaraldehyde. Maybe
you could check this out?
     The next helpful thing would be some sort of determination as to
archivalness of all four.
     Chrome alum was always the hardener, AND clearing agent, mentioned
"back in the day". Then, I started seeing mentions as to chrome alum
causing problems--shrinking the paper, creating graininess in gum prints,
and not being archival. I have no idea if that latter point has some
basis--it only appeared in the lit in the last 40 years. I'd love to hear
from conservators on this list as to their thoughts on this subject, and
scientists/chemists as to their thoughts on from greater to lesser toxicity
of the 4 options.
     In my first foray with chrome alum, it was crystally, the paper was
bluish with the coating, and it coated unevenly. My gum layers also came
off in chunks. Since with all three other hardeners I never had these
problems, I decided to abandon it as hardener of choice. But Sandy King
uses it all the time and it works great for him with carbon! The fact that
it takes longer to cure is of no consequence to me--I don't use up all my
paper in a couple days :).
     I am placing an order to a chemical company soon, and thought I would
order some formaldehyde and give it a try. Sarah Van Keuren is positive
about formaldehyde use. I had a stack of formaldehyde hardened paper that
someone gave me years ago that worked great, but Judy's experience with
outgassing has scared me, too, as well as glyoxal's yellowing problem.
Maybe we can get around glyoxal's yellowing by rinsing the paper, but how
about in 50 years? I've heard that both glyoxal and formaldehyde aren't
very good for you, so my bottom line is, it all sucks.
Chris

----- Original Message -----
From: "Bill William" <iodideshi@yahoo.co.jp>
To: <alt-photo-process-l@skyway.usask.ca>
Sent: Thursday, July 15, 2004 8:16 PM
Subject: Re: Gelatin hardening question

> I don't knopw if it has been mentioned since Ryujii posted
> this, but I will.
>
> I may be reading Ryujii wrong, but I view:
>
> > Christina posted a comparison of glyoxal and glut
> hardened sizing for gum dichromate process some time ago.
> She uses 2.5% glut solution that came from the same source
> as mine. So you might be interested in
> digging the archive for that post. Both she and I
> found that much less glut is necessary than the amount of
> glyoxal that is commonly used to harden gelatin for
> sizing.
>
> as suggesting a sort of endorsement of Glutaraldehyde by
> Christina... I do not know where she stands on this at the
> current time, but I think it prudent to be aware that
> Glutaraldehyde is suspected as being the cause of what is
> known as "Darkroom Disease"...
>
> Quoted From:
> http://www.clt.astate.edu/RadSci/PDark.htm
>
> DARKROOM DISEASE
>
> WEB REFERENCE SITE
>
> For Glutaraldehyde, Aldehyde, and Solvent Sensitivity
> Information
>
> This site exists in memory of Marjorie Gordon, New Zealand
> radiographer, educator, and friend, who pioneered
> awareness of darkroom disease.
>
> Sensitivity to chemicals used in radiologic film
> processing has been called "Darkroom Disease" and has been
> attributed to some occupational disabilities, although the
> cause and effect has been disputed. Glutaraldehyde, the
> hardener used in x-ray developer solutions, has been the
> prime suspect, although other chemicals are also under
> investigation.
> ------------end of quote.
>
> While Glutaraldehyde may be a much more rapid hardener,
> given the proper conditions, chrome alum works just fine.
>
> Ray
>
>
> Why break a leg just to get to work early?
> RR
>
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Received on Thu Jul 15 21:13:00 2004