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>Judy said:
>aside from making the linkage of the glyoxal more permanent, it preserves
>it -- the working solution otherwise goes off in a couple of days,
>polymerized -- at least mine did. And with students hardening paper all
>month, I was running out of glyoxal too quickly. However, Paulchemprof
>suggests trying sodium bicarbonate instead, for a reason I didn't
>understand, but I will....
cheaper, safer and has been used traditionally for this purpose for a long
time.
>Judy
>(endquote)
>* Tox Gunn:
>Many polymerization reactions are catalyzed/made possible/occur faster under
>acidic conditions.Maybe the bicarb is just to buffer the pH a bit higher so
>as to slow the polymerzation down?
It has long been known that an alkaline solution of formaldehyde is the
most effective gelatin hardener. I presume glyoxal works the same way. This
should be fairly easy to test.
As explained in my books, chrome alum made acidic, is also very effective.
I wouldn't worry too much about the acidic aspect of this liquid hardener
if the print is thoroughly washed before drying.
Luis Nadeau
nadeaul@nbnet.nb.ca
Fredericton, New Brunswick, Canada
http://www.mi.net/dialin/awef6t/