Printing on Darks:
Some inks are opaque enough to stand out when printed on darks. Most inks, however, require a white underbase (underprint). Underbase art combines plates of all of an images light colored ink areas. Underbase will increase the hand of the garment design.

It is best to keep the design "open" and to avoid solid blocks of ink to keep the feel light on the shirt. The hand of dark printing with a quality underbase is lighter than spot printing because of the use of the dark shirt to replace dark areas in the image.