There are essentially three ways by which the necessary energy can be applied to a wet-printed substrate. The printed matter may be passed over a heated surface and the thermal energy conducted through the substrate into the ink layer. Secondly, warm air may be blown across the surface of the print, a method particularly effective for drying solvent-based ink via forced convection currents. Finally the energy may be transmitted across space from a suitable emitter and absorbed directly by the molecules that comprise the ink vehicle.