From: Christina Z. Anderson (zphoto@montana.net)
Date: 08/15/03-08:33:40 PM Z
Good evening, list!
I have been in the throes of moving and setting up internet services in
a new place and trying to get all connected, and struggling with a laptop
with a too small keyboard. Microsoft wireless keyboard came to the
rescue--ergonomic, no less. However, I continued through all this to
ruminate on gum printing (I should really give this up and start reading
romance novels).
This is in response to Dave Rose's interest, about a month ago, in
hearing my thoughts/research on gum staining. As I was driving cross
country, I outlined the issue of gum staining in my mind, including all I
have read and experienced, and thought I could share this outline with the
list in a way that seems logical to me. I'll try to reproduce the outline,
below (but it probably will get all off kilter when it goes thru the
internet) and would love comments/addtions, as I usually miss the obvious
(duh).
Also, Judy, I can't believe I overlooked in my notes this bit of
research: in the BJP of April 1908, it was a Mr. C. Wille who demoed gum and
did the pigment/gum titration stain test, using 1-7 pts gum, so unless
Anderson's stain test is before this date, Mr. C. Wille is the culprit
behind the fetishistic stain test, that b*&()!!!.
In my mind, the problem is, in the large picture, degraded highlights
or whites of the paper. So it looks to me to be something like this:
I. Degraded Highlights
A. Insolubilization of the gum/pigment on the paper
1. Insolubilization due to light exposure
a. Fogging or accidental non-image exposure
b. Overexposure
2. Insolubilization due to other than light exposure
a. Acidity of gum solution--either sour or by adding acids
b. Dark reaction
c. Continuing action
d. Heat, excessive
e. Certain pigments which are purported to cause
non-exposure insolubilization (mentioned a number of times throughout
history, but no mention of which ones specifically--perhaps chromiums)
B. Pigment stain
1. Insufficient sizing
2. Improper proportion of pigment to gum, especially significant
when using some colors that are highly saturated, finely ground, or
generally considered "stainers"
3. Too much liquid so that the gum viscosity is lessened enough to
allow the pigment to settle into the paper fibers
Chris
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