Example of overpigmented tricolor gum
Here's an example of an overpigmented tricolor, the color layers
mixed to the same color saturation I would use for a one-coat gum
rather than being adjusted to accommodate the additive effect of the
three layers. This is the kind of case where I would recommend
reducing the pigment in order to fix the problem of the print being
too dark (and when someone says their tricolor gum is "way too dark"
something like this is what I'm imagining). Hope that's clearer.
http://www.pacifier.com/~kthayer/html/overpigment.html
Katharine
On Sep 26, 2007, at 11:50 AM, Katharine Thayer wrote:
Oh, if you're talking about those prints, then absolutely the
pigment shouldn't be reduced. But I thought he was talking about
something else, since neither of those prints is at all dark.
And I agree, the danger is when people start calibrating for one-
coats and then use the same mix for tricolor; that's when you can
overpigment the layers and get the print too dark.
Thanks for chance to clarify,
kt
On Sep 26, 2007, at 11:17 AM, Marek Matusz wrote:
I was thinking about the two prints that CHarles has shared and I
did not see the evidence of overpigmentation there. There is some
evidence of color imbalance, that is the concentrations of
pigments relative to each other is off. This is not surprizing in
view of the pigments that he has chosen. In principle the pigment
concentration of the three primary colors should be established
before the first negative is printed.
So I assumed he had his pigment concentration about right (maybe
that was not a correct assumption since I have not seen the print
in question).
In principle I would agree with you that both should be considered
when troubleshooting. This would be even more so for people coming
from monochrome gum printing as they would tend to print their
three primary color layers too dark. That's how I started.
Marek
> Date: Wed, 26 Sep 2007 09:21:10 -0700
> From: kthayer@pacifier.com
> Subject: Re: two questions about gum
> To: alt-photo-process-l@usask.ca
>
>
> On Sep 26, 2007, at 6:18 AM, Marek Matusz wrote:
>
> > Charles,
> > I would say you should adjust your curve and not cut your
pigments.
> > Cutting down on pigment will result in whimpy and grey looking
print.
>
> Since there's no standard for how much pigment to use per layer in
> tricolor gum, I can't see how it makes sense to characterize the
> result of cutting down pigment as a general statement. Cutting down
> on pigment would result in a wimpy and grey looking print only
if the
> pigment was at the right concentration in the first place, in which
> case it would make no sense to cut down on the pigment. My
> recommendation for cutting down on pigment only applies to cases
> where the layers are overpigmented in the first place, resulting
in a
> too dark print (where overexposure has been ruled out by
calibrating
> the exposures first) . Reducing the pigment on a dark print like
> this would result in a bright, balanced print, not in a wimpy grey
> print at all. Maybe I should try to print such a print, to show
what
> I mean.
> kt
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