There are times when a printed document containing a spot color needs to emphasize a particular spot-colored element, typically a logo graphic. This is often done by printing the element twice with the same spot color ink. This requires careful handling in the desktop page-creation software, and in the downstream workflow.
You cannot simply print the same element twice with 100 percent of the spot ink, because the second printing will attempt to put ink on top of wet ink. Usually there are ink adhesion problems, and not all the ink gets transferred to the paper. To avoid this, the first impression is often screened 30 percent to 60 percent with the spot ink, and the second impression is 100 percent. The screening allows the second impression to adhere to the paper.
If there is misregistration between the first and second spot ink impressions, you will see an objectionable screened edge showing. To prevent this, PDF Trap Editor can apply the same stayaway that it applies to rich blacks. This is enabled by the Treat As Black setting in the Inks trapping parameters.
In the same way, set a rich black object to Treat as Black so that a choke trap will be applied to its booster colors.
See Also