From: Katharine Thayer (kthayer@pacifier.com)
Date: 10/18/01-02:38:30 AM Z
Sandy King wrote:
>
> It is known that many gummists, past and present, engage in such
> practices as mechanical development, forced development with water
> sprays, rubbing the image with sponges, brillo pads and other
> abrasive tools, etc. etc. Some have even been know to illustrate the
> borders of their prints with hand drawings, painting, and various
> other kinds of decorative information!!! Such practice (excluding
> the latter) *distort* the basic sensitometric principles of colloid
> processes so it is hardly surprising that some of the photochemical
> laws described by Kosar for photosensitive systems do not apply in
> your case.
Good grief... I keep hearing about these mad brillo pad "gummists,"
but have yet to meet one personally or even virtually, as far as I
know. At any rate, I wasn't referring to any of this "gummist" behavior
when I said that I believe variables other than light source may have
more influence on contrast in gum than light source per se. I was
talking about the effect that adjusting pigment concentration,
proportion of dichromate in relation to gum-pigment, and/or exposure,
can have on an unmanipulated, still-developed print, which is the only
kind I make. As Judy rightly points out, different pigments have
different curves, complicating the issue further, but that doesn't
change my basic conjecture that with any given pigment, such
adjustments may alter the contrast of the print as much or more than
changing the light source. To determine this unequivocally would require
carefully-controlled tests involving a huge matrix of variables, which
I'm certainly not interested in running myself, and without these tests
it's simply a matter of conjecture one way or the other.
As for Kosar-- I'm sorry, I can't make myself think about Kosarjust now;
that part of my brain seems to be disengaged while I'm spending my days
watching cormorants splashing and eagles soaring in pairs, whistling
their high whistles back and forth. So I can't address the Kosar issue
one way or the other, or even make myself think it matters very much at
the moment. Actually, I don't think it does matter very much whether
Kosar's findings on this question apply to gum or not, since as Sandy
has already aptly pointed out:
>However, the fact that a particular actinic light source give images
>of higher or lower contrast is not particularly significant since we
>can adjust the contrast of most processes by various means.
which was exactly my point.
Katharine Thayer
As
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