From: Judy Seigel (jseigel@panix.com)
Date: 02/03/03-09:30:43 PM Z
On Mon, 3 Feb 2003, Gordon J. Holtslander wrote
> One of my co-worker has given me a cast-off container of gelatin. Does
> anyone know of an easy way of determining the bloom rating of this?
Gord, as far as I know it doesn't matter -- I think under 250 is "soft,"
and you might tell by making a 3% solution & letting it set at room temp.
Soft will squish with the finger, hard, less squishy. But handling is
extremely subjective anyway, no matter the "rating" (as we see from
disagreements about practice on the list).
Generally speaking though, I'd say a 3 % solution is safest no matter the
'bloom" -- more can get too slippery and clog the paper pores, less may
not size enough so you get a bad reaction -- worse than no size at all in
my tests. Or then you might need two coats which is a double pain.
So you start with maybe half the water, sprinkle the gelatin on top of it,
stir a lttle & let soak about 15 minutes, then add balance of the water &
heat to 140 degrees or so, and --- maybe if you're not yet devout you want
to save trouble by brushing on the gelatine, which is of course easier,
but for the devotee, tray soak is better. (I expect a chorus of
disagreement, but we've been there.)
Anyway, let it dry and then harden one piece and don't harden another. Try
with a little print, or better yet a 21-step -- it it "works" -- you don't
need to harden, it's hard enough... But I've never yet done a test of
hardened vs. unhardened where the hardened didn't clear better -- of
pigment stain. !
As for what to try with... A good beginning is equal parts gum and
dichromate solution, but it also depends on a million variables -- so you
adjust, but to get the feel and sense of the ballpark, 1:1 won't be far
off.
The paint just goes along for the ride, but if you start with a strong
pigment you don't need as much, so its bulk doesn't become a big factor in
the equation. I'd also suggest starting with a color that makes tone --
that is, not a pale yellow. Blue or red is good. Even black or brown.
Oh, I get hungry just talking about it !
But... bad-news-Bertha has to add... if you run into trouble, do NOT
assume it's the process. Children's paints can have god knows what in
them, and many of those additives, good for kindergarten, are bad for gum
printing-- either dispersal agents which disperse the paint so far into
the paper it won't clear before armageddon, or fillers, which bulk it up
but mean you only get a very faint tone.
What you might do is get just one tube of a good quality paint in a known
useful color (maybe Winsor Newton quinacridone red, a brand you can get
locally & in the cheapest bracket, or maybe thalo blue) as a bench mark.
For what you describe, incidentally, the process colors might work very
well: thalo blue, quinacridone red, and winsor yellow in art supplies,
probably something like cornflower blue, fire red, and golden yellow in
kid's paints.
you're going to have a good time... (but don't get your hands in the
stuff).
Judy
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