Trapping is the procedure of spreading and choking colors where they touch.

In the example above, the circle on the left has no trapping, so when it is printed there could be a misregister of the colors, showing the bare surface of the disc or paper. The circle on the right has had trapping applied to help hide the misregister of the press. These examples are greatly exagerated, but keep in mind that silkscreen printing is much less accurate than the the offset printing of the CD front cover.

Trapping requirement for silkscreened discs: 0.33 point

If you supply films, the trapping must be done by your designer or by the film service bureau. Some trapping jobs are very complicated so don't be surprised if it isn't done right the first time. Keep the job simple to expedite the film-making process.