MacDougall explains how to print a process-color graphic using low-tech, manual equipment,
I carefully controlled all the screen exposures, and the stencils washed out easily and produced clean, sharp images, with the emulsion completely cured. Without a microscopic micrometer, it was hard for me to judge comparative results between the film and the stencil. I looked for the smallest dots and checked to make sure they were in the stencil. The further I got into this process work, the more I saw the need for some basic measuring devices.
Time to print. Temperature in the shop was 65∞F, humidity steady at 49%. I used three types of material: some 10-pt card stock, some vinyl, and some acid-free fine-art paper. Cyan was the first color I printed. I quickly realized a few things. Everything in the image was printing—if it was on the stencil, ink went through it. There was no moiré. That was a relief! The cyan color bars matched the proof, and if I had a densitometer, I could have been a bit more exact. In any case, it looked good to my untrained eye. Unfortunately, the squeegee still was showing streaks on the flood and the print! I compensated by using a thick flood and applying another quick buff to the squeegee with 300-grit sandpaper. That seemed to work. Best of all, I didn't appear to lose fine detail. The 90% dark areas stayed open.
Yellow was next. The worst problem I experienced with the yellow was trying to see to adjust register. I noticed after the run that the pure yellow was much brighter than the proof, and I had also lost a bit of detail in my 5% coverage. Uh Oh.
Magenta came third. I expected a visit from the evil Dr. Moiré, but he failed to appear thanks to Chromalogic's screen angles and the 55-line halftone and 380-thread/in. mesh combo. Staying in register while printing manually required me to be consistent with my squeegee pressure and angle. This would be so much easier on a semiautomatic press. My sloppy screen cleaning produced a pimple right between my grandson's eyes—amazing that one blocked dot out of 907,500 possibilities can land where it is most visible!
Black provided the snap. Although the coverage was minimal, it made the final print jump! Some junior-grade moiré showed in the 5-10% color bar—but not on the image. After seeing all the colors down, I realized I could have been a little more accurate with registration. There was quite a difference between the results on the different materials. Good to know.
I have to say I was impressed with the final result (Figure 2). I know that improving only a few of my procedures could make my results even better. And if I had some rudimentary testing equipment, look out! Manually printing process-color graphics might still have a future. That will come as good news to young Joshua. He's getting tired of those 22-color art prints. "Get modern, grandpa! Go process!"
The opinions and recommendations expressed in this column are Mr. MacDougall's and not necessarily those of Screen Printing magazine.
Author's note: Part 1 of this process-color-printing series appeared in Dec. '05, p. 60; part 2 in Feb. '06, p. 52; and part 3 in Mar. '06, p. 52. Read more about Chris Taylor and Chromalogic in Screen Printing, Oct. 2005, p. 58.
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