What is trapping in prepress and why is it used?

• A. Trapping protects the edges by raising borders to prevent tearing.
• B. Trapping ensures color consistency across platforms.
• C. Trapping reduces file size by merging colors.
• D. Trapping compensates for potential misregistration by slightly overlapping ink areas.

Answer: (D)

Trapping in prepress is adding a tiny overlap where two colors meet so that if the printing plates or inks don’t line up perfectly on press, there won’t be visible gaps along the edges. This small overprint makes the boundary appear continuous even when there’s slight misregistration, ink spread, or substrate movement. The amount and direction of the overlap are chosen based on the inks, paper, and printing process to keep the edge clean without creating obvious double-impression. It’s not about protecting edges from tearing, ensuring color consistency across devices, or reducing file size by merging colors. The goal is a seamless color boundary despite inevitable printing variances.