ÜberdruckenTrapping

ÜberdruckenTrapping, often simply referred to as trapping, is a pre-press technique used in the printing industry to prevent unwanted gaps or "white lines" from appearing between adjacent areas of different colors when printed. This phenomenon occurs due to slight misalignments in the printing process, where the ink from one color may not perfectly overlap the ink from another.

The core principle of trapping is to intentionally overlap the ink of one color slightly into the ink of an adjacent color. This overlap, known as a "trap," creates a small margin where the colors merge. The amount of overlap is typically very small, usually fractions of a millimeter, and is determined by factors such as the printing process, paper type, and ink characteristics.

There are two primary types of trapping: spread and choke. A spread occurs when the lighter color is spread out to overlap the darker color. This is common when printing light colors on top of dark colors. A choke occurs when the darker color is contracted or choked in to overlap the lighter color. This is often used when printing dark colors next to lighter colors.

The decision of which color to trap and in which direction (spread or choke) depends on the visual impact. Generally, the trapping is applied to the color that will be least noticeable or that will create the least undesirable visual effect. For example, trapping a light color into a dark color is often preferred because the slight spread of the light color into the dark is less visible than a dark color spreading into a light area.

Modern digital pre-press software often automates the trapping process, analyzing artwork and applying traps based on predefined rules or user-specified settings. However, understanding the principles of ÜberdruckenTrapping remains important for designers and pre-press professionals to ensure high-quality printed results.