Today we’re going to talk about a somewhat arcane printing term: trapping.
While typically not an issue when printing full-color pieces, trapping is most frequently required when printing 2- or 3-spot color pieces, particularly when the colors are of equal value or when a lighter color is printed against a darker color background. As illustrated in the image above, when colors overlap there can be a mis-registration on the press that will leave a thin white (the color of the paper) border around the overlapping color. To compensate for this problem, printers will take the artwork file you’ve supplied and generate traps if and when needed using specialized prepress software.
Trapping: Chokes and Spreads
There are two types of traps (additional printing terminology terms you might have encountered along the way): chokes and spreads. A choke is a trap that brings an outside color (i.e., background color) into the outline of a shape (e.g., a letterform). A spread is a trap that extends or spreads the color of a shape into the background color. The amount of trapping required depends on the quality and speed of the printing press as well as the kind of substrate (i.e., paper, plastic, foil, etc.) being printed. Ink will naturally spread in absorbent paper stocks, whereas coated paper stocks and other substrates leave no margin for error.
Trapping is typically handed by the pre-press department at your printer, but graphic designers need to be aware of the issue when creating printed materials so as to avoid problematic issues where colors overlap.
If you have any questions about trapping, give us a call (330-597-8560). We’re happy to help you get the most out of your printing project.
