Re: glyoxal yellowing - is this old news?

[Judy Seigel <jseigel@panix.com>]

Logging on, one's first greeting is of course the SPAM. Today I find "get
a bigger penis naturally," among other enticements.  Equally interesting,
natural or not, the Great Yellow Father has goofed on a package. We could
see that as inattention to mere silver gelatin, except, like they say, one
swallow doesn't make a summer (tho who knows, maybe it does-- any
ornithologists in the wings?).

Meanwhile, here's my experience with yellowing of glyoxal-hardened gelatin
(we did discuss this a couple of years ago, though I've done some testing
since then).

I've found yellowing -- slight overall, but more distinct on the edges
where gelatin tends to build up -- when the paper was stored in the dark
BEFORE ANY PROCESSING IF NOT RINSED AFTER THE HARDENING.  Or I guess that
should read: if not rinsed after the hardening, if the paper wasn't used
within maybe two months, there is sometimes tho by no means always some
yellowing, mostly on the edges.

However, it washes out -- either in a long plain-water soak or regular
clearing bath... I've never seen it in a print.

However again, if you rinse the paper after the hardening, it doesn't
happen either, or not in my experience, no matter how long you keep the
paper before using.  However again again, if you 're going to rinse, you
need more than a 2-minute hardening bath. I've found 5 minutes fine.  If
you rinse after 2 minutes, the gelatin apparently hasn't been fully
hardened, leading to pigment stain. (I figure that figures.)

On the 3rd or 4th hand, I use only 15 cc glyoxal to a litre of water for
the hardening bath... I think 25 cc is more usual. In which case, maybe a
2 minute bath is enough even with a rinse. I didn't test that.

cheers,

Judy


On Tue, 14 May 2002, Sandy King wrote:

> Clay,
>
> I have seen yellowing of the sizing of papers hardened with glyoxal
> on several occasions. For that reason I now avoid the use of glyoxal
> and use chrome alum instead.
>
> In some cases the yellowing may be reversible as someone suggested at
> one time during a similar thread.  I don't recall exactly their
> recommendation but you might try a 3% solution of sodium bisulfite or
> potassium metabisulfite if you have one of these on hand. Just let
> the print soak in the solution for 5-10 minutes and then wash in
> running water for another 5-10 minutes. This is the procedure I
> follow to eliminate the yellowing of carbon prints developed on paper
> that results from bichromate leeching into the paper.
>
>
> Sandy K.
>
>
>
>
>
> >I just pulled out a palladium print that I had sized after printing
> >about a month ago, but had forgotten to finish with a gumover layer.
> >The sized area had yellowed tremendously! Has anyone had any a
> >problem with the paper yellowing after sizing with gelatin and
> >glyoxal? I seem to recall some discussion of this a while back, but
> >can't find the exact thread. Does chrome alum resist yellowing
> >better? And where do you get chrome alum? Neither B&S, Artcraft, or
> >the Formulary carry it, at least on their web pages.
> >
> >Thanks for any help.
> >
> >
> >Clay
>
>
> --
>