When your printed materials are not given adequate drying time, they tend to set-off, the underside of the sheet above it. Eight hours is adequate time for most jobs to dry. When printing is cut, a clamp puts pressure on the printed material and can cause ink to spread or set-off if it is not completely dry. There are three major factors which determine the amount of drying time. The main bases for printing inks are oil and rubber.
Rubber based inks take a longer time to dry.
Paper can also affect the amount of drying time. Coated stocks dry by oxidation. Ink sits on top of the paper and is dried by air. Uncoated stocks dry by absorption and oxidation. Much like a paper towel, uncoated stocks suck the ink into the paper.