overprinting

Overprinting is a printing technique in which one ink is printed over another, so that the bottom color remains visible where the top ink does not fully cover the substrate. The final color is the result of the interaction between inks, and overprinting can create color blends, halos, or subtle tonal shifts that are not achievable with knockout printing alone.

In practice, overprinting is closely related to knockout and trapping. Overprint means the top ink is laid down on top of the underlying ink without removing it, allowing the bottom color to contribute to the final area. Knockout removes the underlying color in the area where the top color is applied, so the top color sits on the substrate alone. Trapping is the deliberate overlap of adjacent inks to prevent gaps caused by misregistration or dot gain, ensuring a continuous printed area.

Applications of overprinting include creating controlled color interactions for logos, text, or decorative elements, especially on saturated or dark substrates. It is also used to achieve deeper or more complex hues by layering inks, and to prevent white gaps at joins or edges. Designers sometimes use overprint to maintain contrast and legibility in specific brand treatments, though text on colored backgrounds is typically set to knockout for readability.

Practical considerations include proofing and prepress decisions. Designers and printers must specify overprint settings in the artwork and check proofs to verify the final appearance, since overprinting can behave differently across press types and substrates. Software tools in page layout and vector graphics programs allow explicit overprint or knockout settings, and trapping should be planned to accommodate substrate characteristics and printing tolerances.