Multicolor printing
The multi-color printing is in all modern printing technique used to create colored print products . Printing machines for multi-color printing contain a separate printing unit for each color. The most common form of multi-color printing is four-color printing with the standardized basic colors cyan , magenta , yellow and black ( CMYK ), the process colors .
Due to the pigments that can be used, four-color printing can only cover part of the color space that can be perceived by humans . For colors that are outside the CMYK color space, additional printing units with additional colors are required. Modern printing machines can therefore be equipped with up to ten printing units (each for one printing color). For luminous colors , extreme color tones, metal pigments or corporate identity colors , which belong to the spot colors , special pigments are required in the printing inks and accordingly additional printing units are required for each additional printing color. With halftone printing, the grids for the colors are arranged at different angles so that they essentially do not overlap.
Gold as real gold, silver as real silver and other metal tones based on bronze or aluminum pigments have special requirements. In order to achieve the metallic luster, in addition to the desired color, the shape of the printing ink pigments must also be adhered to. An aluminum pigment only gives a gray color, for the silver luster, mini-flakes are required. Iridescent colored surfaces (which reflect differently depending on the viewing angle) naturally also require separate inking units and printing processes. Two-color printing machines can only display two freely selectable colors and the color gradations in between. They are therefore mostly used in commercial print shops. A standardized color model for multi-color printing is the Hexachrome color system developed by the Pantone company .
An exclusive form of multi-color printing is the printing of seven printing colors with special printing processes . It is used to achieve good art prints, for example for painting reproductions. Together with the white of the print medium (art paper), eight color components are the technical basis for achieving the color location of each printing point from the color space of the original. The color space that can be achieved with the method can thus be enlarged. The Photochrom print is a Vervielfäligungsverfahren the multi-color printing.