Flexography is the major process used to print packaging materials such as: containers, cartons, sacks, bags, disposable cups, labels, tapes, envelopes, and wrappers of all types. Flexograhic inks are very similar to packaging gravure printing inks in that they are fast drying and have a low viscosity. The inks are formulated to lie on the surface of nonabsorbent substrates and solidify when solvents are removed. Generally solvents are removed with heat, unless U.V. curable inks are being used.