ich Black is used to refer to a mixture containing the four process colors: cyan, magenta, yellow, and black (CMYK) colors. This is necessary because no black ink is truly black, and the combination of the four inks will result in a denser black, or rich black. The printing industry has many definitions of rich black. After much testing and calibration, 4over has selected the CMYK breakdown that works best with our system and presses:
Here is a simulated comparison of just black, and the 4over rich black:
4over does not recommend using CMYK values higher than these. Using too much ink will cause the final print to be muddy, and will have a higher chance of smearing.