QTR-Quadtone RIP

Hi all I am trying to learn about creating digital negative profiles from scratch and the part that I’m struggling with is with choosing ink crossovers and ink limits. (I understand linearizing as I’ve done it before for normal printing with my i1pro and the QTR-Linearize-Data app)

I’m testing things out with cyanotype for now and what I want to achieve is a 2 part gray ink curve.

I’ve printed out the ink separation image with 100% ink limit and then again at 75% which is where the K channel gets its first white on the 100% patch. From looking at the print I can see that K and Y have similar UV blocking as do LK and C (for my particular exposure unit). So my thinking is to combine those two sets of inks so they can fill each other in and make less grainy tones.

My plan is to make a profile where Y follows the K curve and the combined ink limit of those two inks will be equal to 75% (say LIMIT_K=40 and LIMIT_Y=35). And C follows the LK curve and likewise they combine to equal 75%.

The problem now is, since the combined inks will block differently to the individual inks in the separation print, how can I find an actual crossover point for LK+C?

Any help appreciated

Hi ebenostby thanks for sharing your thoughts and experience.

I mostly agree with you about just choosing a crossover based on K and LK and linearizing to smooth things out. I was just wondering if there was a more absolute way with combined inks.

I’m going to try some things out (cyanotype is cheap after all!) I’ll post again when I get some results :)