From: Jack Brubaker (jack@jackbrubaker.com)
Date: 04/14/03-03:00:30 PM Z
I am so glad to hear some comments on acrylic sizing. It's all I have used
to size for gum. My standard has been to use Liquitex Matte Varnish 1:1 with
water. I have had a large supply of the old matte varnish that I have used
for years. I just realized it is no longer made. Don't know when they
changed to the current product line but the Liquitex handouts at my local
shop no longer include the Matte Varnish. I spent this weekend testing six
Liquitex and Golden products that seemed promising. I diluted each 1:1 with
water and brushed on samples of two papers. One set was on Lana the other on
Fabriano 100-100 cotton. Neither is a paper that is great for gum. Even with
sizing Lana seldom prints clear whites. None of the sizes I used printed
good whites on Lana. Both papers printed best with Golden Polymer Varnish
with UVLS (Satin). The UVLS is a UV blocker that is to prevent fading. It's
of no importance in gum printing since it will be under the image, but that
's the way it is sold. The other products I tried include:
Golden Poly Varnish with uvls (gloss)
" " " " (Matte)
" Matte Medium
Liquitex Matte Medium
" Gloss Medium and Varnish (that's one product not a mix I made)
The Golden varnishs seem to be consistantly better than the other options I
tried.
I also tested my old size as a standard to compare the above. However the
last dregs in the bottle of diluted acrylic had gone bad (turned yellow) and
didn't work as a size. I have had diluted acrylic grow mold before but never
turn yellow. I usually mix what I'm using that day as I go but I used to add
a few drops of ammonia to the dilute mix and that seemed to keep it from
molding.
This is only a beginning point for testing sizes. The interesting thing I
saw in this limited trial was that both papers had a better light tone with
the Satin Golden varnish. I was printing a 21 step scale on each size with
the same black gum mix. On the other sizes the lightest tones to print broke
up in a very visible texture of light pigment-no pigment. The Satin held a
thin light tone with little tendency to break up. I didn't get as clean a
white as I am used to getting with my old size on any of these trials. More
work needed but I think I learned where to put my efforts.
What acrylic size are others using? I have a real interest in being able to
size without using the offensive chemicals associated with using gelatine
size. Perhaps I should be looking at other sizes beyond acrylic...
Dave, two coats! I never tried that. I suppose each retains its open texture
needed to hold the gum even though it is a thicker layer with two coats. Or,
do you use a more dilute solution with two coats?
I have felt so smug having a size that worked well for me for 35 years. It's
pay back time.
PS I thought that everyone was using gelatine and I was the odd crank. Glad
to hear I'm not alone.
Jack
From: FotoDave@aol.com
Reply-To: alt-photo-process-l@skyway.usask.ca
Date: Mon, 14 Apr 2003 14:48:35 -0400 (EDT)
To: alt-photo-process-l@skyway.usask.ca
Subject: Re: Mixing a light pigment for gum
either the sizing was too much and I could
brush the gum right off, or it was too little and the gum stained in grain
in the bumps of the paper, or the 2 coats of 1:10 was so uneven that I got
spotty leprous naked bodies.
Chris,
I think the leprous effect is due to too much dilution that the medium
cannot form a continuous film. The acrylic manufacturers do warn about too
much diulation, and they call this "mud crack" effect (if you look at a
whole big area, it does look like mud cracks somewhat.
(I tested 50/50 matte medium, 1/10 matte
medium 1 coat, and 1/10 matte medium 2 coats)
I almost never use 1 coat, always 2 coats or more. Maybe it is just
psychological or the effect of engineering training which says that
averaging even outs random noise.
But considering your test, the first test was 1+1, the second 1+9. The jump
is high. I would, for example, test 1+1, 1+3, 1+6, 1+9 at the same time.
Dave S
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