Ink film not fully dry.
Make sure the ink film is thoroughly dry. An oxidizing ink should take 24 to 48 hours to thoroughly dry. Many variables exist, including substrate, fountain solution, ink coverage, and ambient conditions.
Ink is over-emulsiﬁed.
Check pH and conductivity and Brix level of fountain solution. Run less fountain solution to achieve proper ink/water balance.
Chalking (ink not binding to substrate).
Certain papers can be very absorbent, leaching away the ink vehicle and leaving the pigment unbound on the surface.