From: Judy Seigel (jseigel@panix.com)
Date: 07/16/02-09:19:43 PM Z
On Tue, 16 Jul 2002, Breukel, C (HKG) wrote:
> I was wondering if a exposed, developed and dried (hardened) gum layer
> is still removable. What I mean is; suppose your first processed
> gumlayer has still too much colour in the say the highlights, if you
> apply the second coat, can you than remove a bit of the first highlights
> during water development with say a brush?
>
> Or is the first layer so strongly attached to the paper fibers, you can
> not remove it anymore after it has dried?
>
> My own findings are a bit inconclusive.
You're right, Cor -- the answer is, "it depends." One way I've found that
nearly always lets you get SOME of the previous layer off is a looooooong,
and I mean LONG soak in water, anywhere from 3 or 4 to, say, 24 hours.
This softens up practically anything, then you can brush a bit with
something or other and reduce the tone somewhat -- according to the
paper (a soft paper will be more yielding) and the layer itself.
If the gum layer was developed *hard*, that is, with a higher ratio of
dichromate to gum arabic and a longer exposure, it won't be so yielding.
But if the ratio of gum to dichromate is high, and/or the exposure
relatively light, the resultant layer is "softer," and more malleable.
The basic idea of the long resoak, incidentally, is courtesy of R.
Demachy, who mentioned it in one of his how-to's, among other strategies
-- including some I've tried & failed to replicate. But he got so much of
the possible manipulation & strategy of gum right off the bat, de novo,
that it's awesome. (It took later generations, starting with Paul
Anderson, to muck it up.)
HOWEVER, except for maybe selected spots where you can rub up a bit of
paper white, or lighten tone as mentioned above, it's still a gamble.
Unless you're very lucky & devise a way to brush with great even-ness,
almost mechanically, the resultant tone in my experience is likely to have
a scrubbed look, that is, be unattractive, and may also degrade the paper
surface. True, you plan to put another layer on top, which may cover a
multitude of sins, but if the paper is really degraded, next coat can get
ugly.
A better way, if you have more tone than you like, might be add some white
to the next layer. Or even just a thin layer of white alone.
Which white? Again, this is subject to all the other variables and the
brand of paint, but zinc white, or "Chinese white" (same thing) don't have
the same covering power as titanium white. In fact, if you get the mix
right, just a very light layer of titanium white with a relatively small
amount of gum (so you don't get too much body) may work. Try brushing it
off in some areas, leaving it on the highlights (if, as you say, they're
the problem).
Of course as we've discussed on the list before, sometimes the reverse
occurs and a layer of gum goes west with the next coat. My HYPOTHESIS
about this is that it was quite soft to begin with (high ratio of gum, not
strongly exposed), and therefore vulnerable. Or the next layer was just a
killer -- werewolf. C'est la vie en gomme.
PS: For a bit of white in an area of too much haze, I soak as above, then
GENTLY wipe with a bit of absorbent cotton twisted onto a sharpened
applicator stick.
But to clear a spot completely, nothing beats chlorine bleach, also
applied with bit of absorbent cotton (not to eat up your brushes) -- both
strategies (as I recall) illustrated P-F #2, "Annals of Gum Control," p.
45-6.
cheers,
Judy
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