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RE: sumi ink for gum
Thanks for you comments, Dave. I hadn't thought about flashing (although I
was playing around with a digital Photoshop curve that DOES lessen the
staining effect - by allowing slight exposure where there ordinarily
wouldn't be any).
I think you hit the nail on the head with the "watery emulsion". My
gelatin/hardening procedure has been time-tested (well, a year's worth,
anyway!) and I see no problem when I print up to seven coats of conventional
watercolor pigmentized gum. But the Sumi emulsion is certainly thinner, and
thus sinks in further.
-----Original Message-----
From: FotoDave@aol.com [mailto:FotoDave@aol.com]
Sent: Thursday, March 30, 2000 10:26 AM
To: alt-photo-process-l@sask.usask.ca
Subject: Re: sumi ink for gum
kgerling@ameritech.net writes:
> The paper was sized with gelatin and hardened in glyoxal. The tests were
> made with 21 steps. Yes, Judy, the stain is actually worse in areas of
less
> exposure.
Hi Keith,
My "theory" is that during coating, the emulsion has a chance to blend with
or to soften the gelatin a little. In the highlight where some exposure is
received, the top layer is exposed and hardened. During development, the
exposed layer washes out and at the same time pulls the bottom layer away.
In
the highlight where very less or no exposure is received, no top layer is
hardened, so this pulling-away action is not happening, thus it stains. This
is, of course, just a theory. If you are interested, you can see my
explanation in the archive, search under "gelatin" and "hardening." Sorry
that I don't remember the exact title (subject line).
This solarization (staining on no-exposure region) happens more if your
gelatin is not strongly hardened or if your emulsion is watery.
If your negative does not have a very-high density area (like specular
highlight), then you probably won't see the solarization effect at all
because all area will receive some exposure. In any case, a short flashing
will take care of the solarization effect since now the whole image receive
some exposure (a longer flash, if calculated properly, extend the scale; but
that's a different effect).
That is assuming your paper has reasonable sizing. If the pigment has
penetrated into the fiber (as in unsized paper), then it is very difficult,
if possible at all, to clear the stain.
Dave Soemarko
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