On Jul 14, 2006, at 9:20 AM, Katharine Thayer wrote:
> Mark, this is related to the point I was making re gum. For many
> reasons, the "natural" exposure times for gum emulsions will vary
> widely, even given the same light source and other protocol.
Just one example of this variation: in the days when I was printing
tricolor with PY 110, PR 175, and either pthalo or ultramarine, the
exposure times were the same for all colors. But last year when I
was working on test prints for different tricolor palettes for my
website (a project that got set aside and I've never got back to it)
I found that I had to vary the exposure times for most of the yellows
and reds rather than exposing them the same as the blue. In other
words, it just happened that the PY 110 and PR 175, both very deep
colors and printed fairly strong, seemed to behave the same toward
the radiation as the dark blue; I just happened by accident to pick
three colors that printed all the same. When I was printing with
those colors, someone asked the list, "When you print tricolor, do
you expose all the colors the same?" My answer was "yes" and other
people answered "no," but the correct answer is "it depends on the
pigments."
Katharine
Received on 07/14/06-05:32:21 PM Z
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