What is overprint? You must understand what does overprint mean as a graphic designer. By knowing the process of overprint, it would help you to gain better understanding to the entire printing process. Overprinting - when inks are printed on top of each other. This can be used to create additional colors, special effect, and silhouettes. Typically, when you produce separations from a document with overlapping objects, the top objects knock out any colors beneath them on the other separations; overprinting leaves the background colors so that all of the inks for the overlapping objects print in the final piece.
Overprinting colors with uncommon inks combines the ink values in the overprinted colors. For instance, if the background color contains 40% Cyan and the overprinted color has 70% Yellow, the overprinted area will consist of 40% Cyan and 70% Yellow. Since overprinting occurs, you would see the color of green shown on the final piece.
When you overprint colors with shared inks, common ink values are not combined. Instead, the ink values of the overprinted are used in the printed color. For example, if a background contains 40% Magenta and 0% Yellow, and the printed color contains 20% Magenta and 50% Yellow, the printed color where the colors overlap will contain 20% Magenta and 50% Yellow. Beside this, overprinting is also used to specify varnished. Varnishes, which can be used to emphasize the display text or enhance the images, can be treated like a clear spot color that is overprinted.
Always consult and talk to your commercial printer before setting inks to overprint since overprinting can increase the amount of ink coverage on the page and may cause problems on the press.