Re: Glyoxal Staining

Hi Sandy,

>I would be interested to know which papers stained after hardening
>with Glyoxal, and how long after hardening did it take for the stain
>to appear?

I've experienced some glyoxal staining on every paper that I"ve testted it
with, including Arches Watercolor, Arches Platine, Fabriano Tiepolo,
Lanaquarelle HP, and several Somerset papers. Gelatin sizing was 5 to 8
per cent of a pretty clear, high bloom gelatin; previously sized papers
were bathed in a glyoxal solution of 5 per cent. However, for testing, I
put all papers through a hot dry mount press which I think accelerates
staining, or at least makes the stain stronger. Sometimes the stain would
be very subtle or even localised in an area, say in a very light streak or
small spots, but more often it was an overall cast. Some papers turned
dark orange-brown, but I don't recall which. Papers treated and left in
the light in my workroom without passing through the hot dry mount press
will exhibit discoloration similar to what Klaus describes after a few
weeks to two months of nearly daily exposure to light. I think that papers
in dark storage don't stain as quickly, but I'm not sure.

>Currently, I treat prints hardened with glyoxal in a clearing bath of
>Sodium Sulfite and Sodium Bisulfite. To date, prints thus treated have not
>yellowed or stained.

I've been successfully clearing with this solution since January or
February of this year.

>Stock Solution:
>
>Water (at 110 degrees F.) 900 ml
>Sodium (Meta)Bisulfite 30 gm
>Sodium Sulfite 30 gm
>Water to make 1000 ml
>
>To make a working solution, dilute stock in cold water at 1:20.
>
>While this solution limits glyoxal's ability to stain the paper, it also
>reverses glyoxal's hardening effects on the gelatin, either partially or
>completely, depending on gelatin type and paper used. Fresh gelatin
>emulsions thus treated may be returned to a soluble state. Occasionally,
>over-soaking in this clearing bath will cause the gelatin emulsion to
>separate from the paper in bubble-like areas that, once begun, will grow in
>size quickly, so I am always careful to limit the length of soak time to
>1-2 minutes.

I've had success in reversing stains which were barely perceptible using
the Sodium sulfite bath mentioned above. In some cases, I would pour a
higher concentration of working solution, like 1:10 or stronger, right on a
particular stain. Such salvage work involves letting the sodium sulfite
work for more than a minute or two, however, and then one risks the scary
growing bubbles. Now, I put everything through the sodium sulfite bath,
followed by a wash, as the last step in my print processing, and everything
is quite clear.

(P.S. sorry to have neglected to set the correct message subject on
previous post.)

Best,

Tod Gangler
Art & Soul
Seattle, WA
Received on Thu Oct 19 18:36:32 2000