Engraving, in its broadest sense, the art of cutting lines in metal, wood, or other material for reproduction through printing. In its narrowest sense, it is an intaglio printing process in which the lines are cut in a metal plate with a graver, or burin. Furrows are cleanly cut out, raising no burr, and then filled with ink which is transferred under high pressure to the printing surface of the press. The earliest known engravings printed on paper date from about the middle of the 15th century. Among the early master engravers were Dürer, Schongauer, and Lucas van Leyden. Wood engraving differs from true engraving in that it is a relief process. During the 19th century., steel engraving enjoyed a short popularity as a reproduction process because it made possible a large number of proofs, but it was superseded by photomechanical processes.