From: Christina Z. Anderson (zphoto@montana.net)
Date: 04/16/03-09:27:20 AM Z
Good morning all,
I just can't leave experimentation alone...after Dave's post about
powdered pigments, and the fact that I had run out of liquid gum and had
powdered gum available, AND powdered pigments for other purposes, and
reading in Barnet's 1898 book about Demachy's dilution of gum arabic, etc.
etc. I found this out:
I found Demachy mixed gum/water in a ratio of 30-35%. Hence I took my
powdered gum arabic from Daniel Smith and did this ratio, in my food
processor. After reading hither and thither that it isn't good to use the
powdered form, takes 4 or 5 days to settle, etc etc. I found that it whips
up really well in the food processor, and after about an hour (?) or at
least while I was measuring pigment powder, it cleared into exactly the same
gum I buy in liquid form from D. Smith. Light amber, viscous, you name it,
and half the price as the liquid form. In fact, I would bet D. Smith uses
powdered arabic and mixes it themselves.
Then, I decided to disprove whether you need to let it sit and soak and
I printed it right away--perfectly fine.
Then, I weighed and measured powdered pigment. By all means, q. violet
is so incredibly fine it suspends in the air and got over my entire kitchen,
so that everywhere I wiped down counters it bled purple. Luckily my husband
is out of town for several weeks because he would've s--t!
Furthermore, I found out that weighing pigments is a crock. The
teaspoon amount of the 6 powders I have varies from 3 tsp to 12 for 10 g!!!
It would seem to me to be much more profitable to mix pigments by volume, or
forget the measures and eyeball.
So then I tested immediately printing a raw umber powder pigment/powder
gum right away to see if it stains, streaks, etc, and sure enough--it is
perfect. On unsized Rives BFK.
Today I will test my nemesis, q. violet. At the 10g/120ml that someone
on this list (Dave?) uses, it was 8 teaspoons of the stuff. Way too
concentrated in my opinion, but if it's gonna stain, it should. If it
doesn't, I'm switching to powder.
My usual morning 2 cents (you know--it is so nice to have people out
there like you guys that even give a rip about this info, because when I go
to school all excited about something inane like powdered pigments they look
at me with blase eyes like I am nuts).
One request: does anyone have Warren's 1899 book The Gum Bichromate
Process who could xerox it for me and I would pay them? I really would like
to look at it. That and Pigment Printing by...can't remember right now...are
two I don't have.
Chris
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