Often in offset lithography printing, large black areas are printed using what is referred to as rich blacks. A rich black contains all four process inks: cyan, magenta, yellow, and black. Rich black is useful in large solids to produce a “darker” black that prints more evenly on the press sheet than simply using 100% black.
A typical rich black mixture is 100% black, 30% cyan, 20% magenta, and 20% yellow. Rich black is often regarded as a color that is “blacker than black.” While this is not accurate from the point of view of color theory, the difference can be seen on the printed sheet.
When using rich black with digital however, the type of digital press must be considered. Some digital presses, because of the characteristics of the toner, actually reproduce better blacks without creating a rich black. Others will reproduce rich blacks much like an offset press. It’s because of these differences in press manufacturers that it is always best to check with your print service provider first before introducing rich blacks into a document.