From: Judy Seigel (jseigel@panix.com)
Date: 07/16/01-12:30:13 AM Z
On Sat, 14 Jul 2001, Katharine Thayer wrote:
> Just for the heck of it I tried this yesterday: a stain test with four
> different concentrations of pthalo blue mixed 1:1 with ammonium
> dichromate on unsized Arches and (just for the heck of it) unsized
> cardstock out of my office supply closet. There was a discernable but
> very faint stain for all concentrations on both papers; neither paper
> showed more staining than the other. The results can be seen on Joe's
> gum forum at Bostick & Sullivan.
It's actually insidious. I had another test set up & somehow thalo stain
got into the act. I used two gums, Winsor Newton and Daniel Smith
lithographers gum, on about 8 papers...
But I should have qualified my comment that I thought the thalo would
stain more without size. Paper used for the FIRST time ("virgin") often
clears well. After it's been wet, the nap of the paper is raised, & the
surface size from mfr washed off, then I find (generally) it stains more
if not sized.
HOWEVER, this batch was all over the map. Both gums on unsized fresh
lanaquarelle stained so heavily you could barely make out steps. Stain on
unsized fresh arches acquarelle was also heavy, though the Winsor Newton
less so. Merten Spiesse gelatin-sized had very little stain, but almost
none with the WN. Similarly the heavyweight Fabriano and Somerset Velvet.
The only real surprise was that Rives BFK shrunk but NOT sized cleared
quite nicely, with both gums making 9 quite regular steps. (All exposed 3
min, still-developed in rm temp water 1 hour.)
I'm not terribly happy that the Winsor Newton tended to clear better than
the lithographer's gum -- $7 or $8 for about 6 ounces is very
disappealing. What put it on the agenda was a class I taught here in March
-- the teacher told them to buy gum arabic at the school store, and all
had the Winsor Newton. I'd never used it, had heard it was NOT good, but
didn't have the heart to rule it out. So we used it -- and it proved
excellent. I haven't tested it against the RGB gum, which is generally
best, and I notice that in several coats it gets what I consider an
unpleasant shiny build-up, but....
New topic: When I logged on tonight I had 5 spams. (How to go into
bankruptcy, secrets of the Internet, lose 10,20,30 pounds, etc), more than
usual. Is this just me, or everyone?? (Last week I got one from I think
it was Lagos offering to make me a partner in some money left behind in a
bank. They'll send it to your bank if you give them your account number &
sample signature.)
cheers,
Judy
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