Re: pigments for gum and PDN

Katharine Thayer wrote:
>
>
> I'm making slow progress but so far my observations may back you up
> somewhat (but not entirely) on the idea of different curves for
> different pigments. I found that starting with the same curve and same
> exposure time (2 minutes) for all, the reds and yellows that I have done
> have developed in 20 minutes and similarly well-stepped, although I
> don't have enough data to say definitely that I don't see a difference
> between reds and yellows. But I do see a definite difference between the
> reds-yellows and the blue (I'm only using pthalo so far to simplify
> comparisons between reds and between yellows). With the pthalo, I
> haven't been able to get the two darkest "steps" to differentiate, even
> with 2-day development. No doubt a curve that adds more negative density
> for the shadows could help that. (I tried cutting exposure to 1.5
> minutes but that was underexposed; I lost the lightest "step" in about 5
> minutes of development.)
>
> But my sense is also that there's too much pthalo in the pthalo. I
> wouldn't have thought til this week that you could get too much color
> without staining, but now I'm thinking that it is so (based on not only
> this but on the way the colors work on top of each other). This is more
> pthalo than I would ordinarily use with my intuitive-by-eye mixing
> method, but I was trying to standardize the colors as much as possible
> by using each color absolutely as saturated as I could get it (I've done
> this by putting more color into the gum, printing, putting more color
> in, printing, til I didn't see any difference in the depth of the
> printed color between two printings).

The point I'm trying to make here is that in my experience, when the
pigment concentration is "right" for each pigment, the same curve for
all three will most often result in a print with the desired color
blend, without additional color adjustment. Here, by trying to
standardize the experiment by using each pigment at absolute
saturation, I forced myself to use a more saturated pthalo* than I
ordinarily would, and ended up with a color that was too strong in
relation both to itself and to others, and that would require a
different curve in order to print a good scale with reasonable
development time, as well as to print a better color balance with the
other colors. But this is an artifact of the experiment, a result of
my attempt to standardize the experimental conditions, and has little to
do with my usual practice, in which I print with the same curve for all
three layers and the color picture almost always comes out the way I
wanted it in the first three printings. Hope that helps clearify my
point,

*So far, pthalo blue and one version of PV19 gamma are the only pigments
I've found that can be printed too strong for their own good; with other
colors, printing at total saturation works fine.
kt
Received on Sat Jun 11 14:23:22 2005