>On Tue, 4 Jun 96 Judy Seigel wrote
>
>When you say you couldn't develop prints coated with gum after 6 or 9
>months, I take it you mean the gum was 6 to 9 months old, and had been
>"preserved" with formaldehyde.
Concerning prints and difficulty to develop, the gum was 6 to 9 months old
"preserved" with formaldehyde and the paper was prepared just before printing.
Sorry my english is aproximative, the explanation was not good .
>The other possibility that occurs to me is that you hardened an allover
>coat of gum used as a size with formaldehyde, then kept the paper for 6 to 9
>months before attempting to print on it.
>
>My experience is that gum "preserved" with a *small* amount of
>formaldehyde kept very well -- about 2 drops in 2 ounces. Mine works fine
>after a year, tho it's true I haven't made a comparison test to see if it
>changed.
>
>On the other hand, paper sized with gelatine and hardened with
>formaldehyde has in the past gone off after a year or so (no matter that
>the books tell us it keeps indefinitely). That is, the paper stained, pigment
>didn't clear -- probably due to progressive hardening effect of the
>formaldehyde.
I'm using different papers and I'm not sizing most of them. The paper used
in this way was not sized.
>Now I'd recommend glyoxal for hardening *gelatine* (tho am also testing
>some other options); it's certainly less toxic and virtually odorless to
>use. Paper cleared better with it than with formaldehyde (fresh paper -- I
>never tested older paper). Any ideas out there on glyoxal in gum arabic?
>
>However, I should add that the working solution of glyoxal doesn't
>keep like the working solution of formaldehyde (which worked indefinitely
>-- you could keep a jug going forever by topping it off when it got low). I
>mentioned this a few weeks ago and since then did the following --
>
>Mixed one jar of Glyoxal with distilled water, another with tap water,
>neither of them used. Left alone on shelf. Less than 3 weeks later the
>tap water had a blobbing homuncule in it -- sort of like the Michelin
>man only translucent -- filling the center of the jar.
>
>The one made with distilled had only a very small cloudlet at the bottom,
>suggesting, what? Impurities in the "distilled"?
>
>Whatever, you can't keep the glyoxal and use it again with that fellow in
>it, which is the only problem I've had with glyoxal. But what that would
>mean for glyoxal in gum I have no idea.
>
>> -using salicylic acid,(described by L.P.Clerc, H. Schneeberger)this method
>> give me satisfaction and I keep this option.
>
>Does the salicylic acid come in different strenths? Or do you buy it
>"straight"?
I buy it straight by a supplier of chemicals for analyse.
Martin
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marbecka@club-internet.fr
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