About traps

When overlapping painted objects share a common color, trapping may be unnecessary if the color that is common to both objects creates an automatic trap. For example, if two overlapping objects contain cyan as part of their CMYK values, any gap between them is covered by the cyan content of the object underneath.

Note: When artwork does contain common ink colors, overprinting does not occur on the shared plate.

There are two types of trap: a spread, in which a lighter object overlaps a darker background and seems to expand into the background; and a choke, in which a lighter background overlaps a darker object that falls within the background and seems to squeeze or reduce the object.


Spread: Object overlaps background. Choke: Background overlaps object.

You can create both spreads and chokes in the Adobe Illustrator program.

It is generally best to scale your graphic to its final size before adding a trap. Once you create a trap for an object, the amount of trapping increases or decreases if you scale the object. For example, if you create a graphic that has a 0.5-point trap and scale it to five times its original size, the result is a 2.5-point trap for the enlarged graphic.