Color Trapping, Setting Up Files for Production

To people new on the scene in graphic design, color trapping may bring to mind an esoteric form of hunting, conjuring up visions of large metal teeth contraptions planted with stealth under leaves in the forest, ready to trap unsuspecting yellow sunrays, falling gray raindrops, or red berries.

Well, that’s an exaggeration, but it’s true that designers and illustrators don’t need to be quite as concerned about color trapping and overprinting, in general, as in previous years. This is because many printers now take care of it for us. With the exception of certain industries, it’s rarely necessary to set up trapping and overprinting when using page layout programs like QuarkXPress and Adobe Indesign.

I still set overprinting and color trapping when using Adobe Illustrator, out of habit. I developed this habit when creating illustrations for the book publishing industry, because the printers did not take care of it at all. Before a book would go to print, we would receive bluelines of the book pages, which would reveal any overprinting errors.

Luckily, making sure that an Adobe Illustrator file is set up correctly for color printing can take less than a minute. When doing preflight on a file, I unlock all of the layers, select everything, and set black to overprint and white to knockout, and I set certain colors to knockout if they layer over black. I also make sure that all the color is CMYK instead of RGB, and that the file contains only spot colors, if that applies.

Being a great hunter isn’t crucial anymore in many situations, in the everyday world, or in the world of graphic design, but it feels good to have trapping skills in case it’s necessary.