From: Keith Gerling (keithgerling@att.net)
Date: 06/16/03-11:14:53 AM Z
Thanks for this helpful information! Yep, my gum indeed IS the Varn
variety, which was so cheap I couldn't resist.
Keith
website: http://www.gumphoto.com
-----Original Message-----
From: Judy Seigel [mailto:jseigel@panix.com]
Sent: Sunday, June 15, 2003 10:05 PM
To: alt-photo-process-l@sask.usask.ca
Subject: RE: a newbie's first post: gum, temperaprint, oil printing,
sizing,and computer negatives
On Sun, 15 Jun 2003, Keith Gerling wrote:
> No, it doesn't smell. But I've been storing it in bright sunlight. Not a
> good idea, I guess. I just noticed a warning on the label: "Pure gum
arabic
> has a limited shelf life. Do not use after six months from purchase". I
> guess I had better get busy...
Because I keep five or six different gum arabics on hand for different
purposes, I rarely use a gallon in a year, and have some that's probably
15 years old. I see NO change in their behavior with age. However, I dare
say ALL have preservatives in them.
Then I bought some of Dave Rose's Varn gum to try, and noticed (for the
first time) it said use within 6 months. Not very likely to happen.
However, I just went up and took a whiff of it, which the label says was
opened August 2001. It smells about the same as gum arabic usually does,
that is, no rotten egg or other disagreeable odor, but what I noticed in
particular this time is how EXTREMELY light, almost water color it is.
My other gums are quite a bit darker, the Daniel Smith gum about coffee
color -- tho it came that way.
Anyway, when I have a chance I'll check the Varn gum (now 2 years on the
shelf) against the original test I made when I got it.... very scientific,
probably, though i guess I should wait til August.
Meanwhile, my theory is,
1. the part about 6 months is simply boiler plate with no meaning
2. it's a way to sell more gum
3. it applies to characteristics evident in offset printing or
lithography, but not evident in our use
4. all of the above, or
5. none of the above.
For the record: the color of gum has NOTHING to do with souring, but is
related to the original gum itself and/or the processing. For instance, a
few years ago they said drought had made the gum darker, which may
possibly even be true. More likely I would attribute the darkness of the
DS to impurities, since some of it does settle in time in a VERY dark
layer on the bottom of the jug.
And/or it can be a factor of oxidation, as galkyd varnish darkened in the
jar after opening, which was explained by the company (Gamblin) as due to
oxidation. Sometimes it did and sometimes it didn't show darker in the
image (the galkyd) -- I just used a VERY thick coat of it poured onto
plaster and it dried totally clear. A thinner coat on paper left a dark
stain. so go figure.
HOWEVER, my tests of gum arabic showed that dark gum and light gum gave
the same final color, except sometimes with yellow, tho in that the darker
gum didn't make the yellow look darker so much as greener... but I never
use yellow as a solo color, and liking the printing character of the dark
gum, I put the issue out of mind.
Judy
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