From: Dave Rose (photo@wir.net)
Date: 12/17/01-11:21:53 PM Z
Greetings from Big Wonderful Wyoming,
I've been printing gum and cyanotype for over ten years. I'm self-taught,
getting my start by reading Crawford's "The Keepers of Light", and later,
Scopick's "The Gum Bichromate Book, Second Edition". I've also experimented
extensively, and have done numerous tests, including the maligned
"gum-pigment ratio test". I was making sharp, fully detailed 16x20" gum
prints years before "Post-Factory Photography" was published, or this
mailing list was established.
Katherine wrote:
(snip)
> But as I've thought about it, I've come to believe that we can't really
> have a meaningful discussion about this without having the complete
> picture, which includes the fact that my experience and data actually
> support the test rather than the challenge to it.
I agree 100% and my experience also supports the validity of the gum-pigment
test. I've done the test on over forty different pigments. My results are
well documented and repeatable. Is the test perfect? No, but it sure helps
to quickly determine a good starting point for gum-pigment ratio.
Judy Seigel's criticism unfounded. The fact is that she *screwed up* the
test to begin with and then (apparently) didn't even bother to re-read the
instructions that she is so quick to criticize.
>From "Annals of Gum Control: Part 1" in Post-Factory Photography Issue 1,
Seigel writes: "Dutifully running this test one day with fresh paper, on a
whim I tried it on preshrunk paper. Oops, the result was completely
different."
Well, DUH!!!.... why bother telling us the obvious?
Crawford wrote: "The test consists of making a series of dots on a sample of
the paper used for printing."
Common sense dictates that "the paper used for printing" is preshrunk,
sized, and hardened. Why did Seigel "dutifully" run the test on "fresh
paper"? Maybe because she didn't understand the basic instructions? It was
a "whim" that led her to try the test on preshrunk paper?! Double DUH....
that's where she should've started in the first place.
Crawford writes about the effect of sizing, the degradation of sizing as
multiple printings are made etc.... as it relates to the propensity of
pigment to stain the paper (see page 212 in Keepers of Light). But Seigel
rehashes these basics and presents them as (her) new observations in
Post-Factory Photography.... at the same time she's slamming Crawford and
Anderson. In my opinion, the Gum Printing chapter in The Keepers of Light
is far more accurate and informative than the 'beginners article' that
Seigel printed in her magazine.
> Today I have run a replication of my early approximations of the test
> and the results come out the same as they did before: (1) stain
> increases directly with pigment concentration, and (2) staining shows up
> in the float test at about the same concentration as staining in
> printing.
Right. The test is simple, quick and easy. But *some people* just don't
'get it', so they have to attack it as invalid. Too bad. This test and its
results are a valuable guide in determining a starting point for gum-pigment
ratio.
Best regards,
Dave Rose
Powell, Wyoming
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