Re: uncurve/curve comparison on Loris' website
That comment (which you chopped the first part) wasn't related to devise curves for gum printing (either tricolor or single layer). It was an independent suggestion (there was two different subjects / issues in that message) about how to get paper white with R1800 inks when using colorized (= no black) negatives (with whatever process - you name - that one is able to change coating solution's ES)...
Quoting Katharine Thayer <firstname.lastname@example.org>:
On Sep 28, 2007, at 1:50 AM, Loris Medici wrote:BTW, what dichromate concentration are you using? You may try to use less dichromate if you use saturated solutions. That way, you may achieve paper white with colorized negatives (despite their DR being lower compared to grayscale / all-inks negatives).Mmm, I have to disagree with this. If the color is right, there should be no difficulty getting paper white if the negative is calibrated properly. I get paper white all the time with colorized negatives and saturated ammonium dichromate. The purpose of the colorized negative/lowered DR is to eliminate the extra headroom in the white, but if you don't get any white at all, something's wrong (my example Exhibit A). After all, one calibrates with the mix one is using, so it doesn't make sense if the negative the calibration produces doesn't work for the mix one is using. kt