Re: Glyoxal amounts
Marek, I used exactly what you're using; 7 g gelatin in 200 ml water,
or 3.5%. I did it just as you say you do it now: 1 cc 40% gyloxal
in 200 ml 3.5% gelatin. I'm not sure what you mean by 2 coats; if
you mean you size and dry and then size again, I couldn't be
bothered, since the usual 3 cc per 200 ml works very well with one
sizing, and I don't see any need to go to two. But the 1 cc per 200
ml produced staining for me on the second coat in, yes, well-aged
paper (these had been sized for at least 3 months when I printed on
them). As I said, I've gone back to the traditional formula, 3 cc
40% glyoxal in 200 ml 3.5% gelatin.
On Sep 11, 2009, at 5:56 PM, Marek Matusz wrote:
Somehow missed this post
Katharine
what gelatin concenration did you use? Glyoxal should be ratioed
to the gelatin, since it reacts with it. My practice is to use
about 1 cc of 40% solution per 7 grams of gelatin in 200 cc of
water. Two coats of this solution work better then one in
preventing stain. Also it is better to use two 3.5% coats then one
stronger 7% coat. At 7% gelatin concentration it is difficult to
coat witout streaks and smears. 0
My paper is Fabriano Artistico, never found anything better than
this paper. Since I always size two or three packs of papers there
is always extra paper sitting around for weeks. What I am trying to
say my paper is aged. My practice is to size fresh paper and then
soak it after a few days in tepid water to shrink it.
Marek
> Date: Tue, 1 Sep 2009 18:03:46 -0700
> From: kthayer@pacifier.com
> Subject: Glyoxal amounts
> To: alt-photo-process-l@usask.ca
>
> About a year ago, in the wake of a hurricane, Marek reported some
> good experiments by which he demonstrated (by coating glass with
> gelatin containing various amounts of gelatin, allowing it to set,
> and then immersing it in warm water to determine how much the
> gelatin softens/swells) that the amount of glyoxal required to
harden
> the gelatin to where it will swell but not dissolve is 1/10 what is
> usually recommended.
>
> I've gone on sizing paper using the recommended 15 ml 40%stock
> solution/ liter,of gelatin solution, or 3 cc in 200 ml gelatin, but
> the last time I sized, I cut back alittle, just to see; I used 1 cc
> in 200 ml instead of 3 cc, or in other words I cut back to 1/3 of
> what I'd been using, but wasn't quite ready to cut back all the way
> to 1/10.
>
> My results were not good; I sized two different papers
(Lanaquarellle
> and Arches bright white) and have been getting heavy staining on the
> second coat with both papers. Not a refutation of Marek's findings,
> but just more data for our database. Marek, have you found that
> your findings on glass have translated to practical success on
> paper? And if so, which papers?
>
> In the meantime, I'm going back to the traditional formula, which
has
> always worked for me.
>
> Katharine
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