From: Sandy King (sanking@clemson.edu)
Date: 12/05/01-11:15:17 AM Z
Christina Anderson wrote:
>
> When I was taught gum printing we used glyoxal, not formalin, because
>of the toxicity of formalin. But then I read the thread on this list about
>the yellowing over time of glyoxal (and can't remember what the final
>decision as to this was) so now I am not so sure what to do.
I don't know what the latest word is either but I have definitely
experienced paper yellowing with glyoxal. That, plus the news that it
apparently goes bad with age, which I had not heard before, drops it
pretty low on my list of hardeners, even though I have a couple of
pints of the stuff on hand!
For a fact I know that Formaldehyde does not yellow paper and lasts a
long time. Over 15 years ago I bought a gallon of the stuff and still
have a lot of it left and it seems to work as well today as the day I
bought it. However, Formaldehyde is real nasty stuff to work with
inside. Even with good ventilation the odors can be very pungent and
you definitely do not want to be breathing them.
On the whole I find chrome alum less obnoxious to work with than
formaldehyde, and it appears to harden the gelatin just as well
without any of the yellowing of glyhoxal.
Sandy King
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