Rich black is an ink mixture of solid black, 100% K, with additional CMY ink values. This results in a darker tone than black ink alone. If you print black alone as 100% K, the resulting black may not be as dark as you might like.
100% K on Screen:
100% K after Print:
We Recommend Using:
C-60 M-40 Y-40 K-100
This will give you a deep, dark, rich black.