Smieglitz@aol.com
Date: 02/04/02-06:25:55 PM Z
Hello all,
Here is my opinion on this issue:
A) The Anderson gum/pigment ratio test does not work for me.
B) I have performed it according to the book several/many/enough times to
know it is does not work for me.
C) I believe the reason it does not work (for me) is that the addition of
the dichromate solution to the emulsion reduces the viscosity of the actual
emulsion and thus creates a thinner mixture that takes longer to set,
therefore allowing more time for the pigment to soak into the paper and stain
it. So the emulsion mixture as it is used in actual practice has a different
viscosity than that used in the stain testing procedure and invalidates any
results from such a test.
D) Several varying opinions about this issue have been expressed so far.
This one can only be answered for the individual practitioner. If the test
gets you close, fine. If it doesn't, well, welcome to the other side. But I
would suggest anyone attempting gum printing actually keep an open mind and
not believe everything you read, whether on this list, in classical texts, or
modern periodicals. One has to do the tests to determine utility for their
own methods. In this case, I find myself agreeing with some on the lack of
merits of the gum/pigment ratio test. Yet, I have been unable to duplicate
results with certain often recommended paper and pigment combinations.
Sometimes we agree and get the same results, and sometimes we don't, and I
really can't explain why. Maybe it's the water or phase of the moon... I
think most of us on this list are certainly competant individuals and are
willing to share our experiences however dischordant they may be with
another's experience. We can all learn from that.
E) "If it ain't broke, don't fix it."
F) "Somewhere is the world's worst doctor."
G) I postulate that a better stain test would include the addition of a
volume of water equal to the dichromate solution in the actual working
emulsion. This would help eliminate the viscosity/drying variable while
eliminating any light reaction or chemical effect from dichromates.
H) I further postulate that longterm dichromate exposure may be the ultimate
cause of the heated debates that ignite here regarding gum printing.
Eliminating the use of dichromate altogether would reduce the incidence of
such flames (particularly in the case of ammonium dichromate). But then we
wouldn't be gum printers, would we?
Joe Smigiel
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