User login

Catching the On-Press Culprit

(February/March 2019) posted on Mon Mar 04, 2019

Whether it was the art, screen, ink, or a combination that caused your job to go south on press, here are four steps you can take to identify the snag – and prevent it from happening again.


click an image below to view slideshow

By Thomas Trimingham

Another common way to control dot gain is using a halftone strip on the sides of your prints. (See Figure 3.) This element adds a small extra step and must be taped off after setup, but it is a wonderful tool for the production department to definitively establish whether the art or the press is causing the problem. If a printed halftone strip clearly shows differentiation between each value and the darker values don’t appear to be filling in solid, then the dot gain is most likely being caused by the art. On the other hand, if the whole strip looks mostly solid (excess pressure will make the 60-90 percent areas totally solid and the 0-30 values almost white), then it’s fair for the art department to suggest there may be a printing issue.

Your artists can adjust their separations for dot gain by lightening the midtones of the halftone curve by 15-20 percent depending on how much gain they anticipate during the run. This allows you to hit your target image value range without compressing the shadow areas in the design too much. Always exercise judgment on this step and consider each design individually because sometimes it may be too much of an adjustment.



Trapping to Prevent Bleeds and Image Gaps
It’s annoying when the underbase of a print is showing when it isn’t supposed to, or when the color of garment is visible because there is a gap between colors. Some printers will attempt to use more pressure to flood the ink out and cover these areas, but this rarely ends well. The best solution is always to create a slight overlap in the top colors of the separations. (See Figure 4.) Known as trapping, this process prevents these problems from happening. 


Terms:

Did you enjoy this article? Click here to subscribe to the magazine.