U of S | Mailing List Archive | alt-photo-process-l | Two tricolor prints

Two tricolor prints


On Sep 25, 2007, at 4:54 PM, Katharine Thayer wrote:

I'm struggling with a similar issue, but finding that I have a different problem than many people have reported. After happily printing tricolor gum for decades by simply inverting the channels and printing greyscale separations, I've been experimenting with a more "sophisticated" approach, with less than satisfactory results. But the problem isn't that the print is too dark when the colors are layered over each other, it's that it's too light and too muddy, compared to the same image printed with the same emulsion by my old habitual method of simply inverting channels
Here's a comparison of an image printed from the colorized and calibrated separations, and the same image printed from separations made by simply inverting channels and printing without further manipulation . The jpeg is rather small because I was intending to append it to a post on another forum, but since the question of calibrating tricolors came up here in the meantime, decided to just put it up on my site; at any rate it's not necessary to see detail; the difference in the vividness of the color, which is the issue of note here, should be quite apparent even in the small images.

I named the page rather cockily "If it ain't broke..." but it is a little broke in fact; the greyscale separations can make a print that's too contrasty, which is the reason I decided to see if I could get an improvement with colors and curves. But so far, I'll take the straight inversions even with blown highlights. This isn't just an anomaly; I did several prints with different pigments and proportions and got the same cloudiness on all of them.

I've been thinking for a while of switching to Prussian blue for tricolors, and these are my first prints with Prussian; it will definitely be my blue of choice for tricolor from now on. I'm still playing with pigments and proportions to balance the Prussian, but the combination I used here gives a fairly close approximation to the original colors.

http://www.pacifier.com/~kthayer/html/tricolorcomp.html

Katharine