PRINTS ARE MADE BY FOUR BASIC printing processes—intaglio, lithographic, relief, and screen. In intaglio printing, lines are engraved or etched into the surface of a metal plate. Lines are engraved by hand using sharp metal tools. They are etched by corroding the metal plate with acid, using acidresistant ground to protect the areas not to be etched. The plate is then inked and wiped, leaving the grooves filled with ink and the surface clean. Dampened paper is laid over the plate, and both paper and plate are passed through the rollers of an etching press. The pressure of the rollers
forces the paper into the grooves, so that it takes up the ink, leaving an impression on the paper. Lithographic printing is based on the antipathy between grease and water. An image is drawn on a surface—usually a stone or metal plate—with a greasy medium, such as tusche (lihographic ink). The greasy drawing is fixed on to the plate by applying an acidic solution, such as gum arabic. The surface is then dampened and rolled with ink. The ink adheres only to the greasy areas and is repelled by the water. Paper is laid on the plate and pressure is applied by means of a press. In relief printing, the nonprinting areas of a wood or linoleum block are cut away using gouges, knives, and other tools. The printing areas are left raised in relief and are rolled with ink. Paper is laid on the inked block and pressure is applied by means of a press or by burnishing (rubbing) the back of the paper. The most common forms of relief printing are woodcut, wood engraving, and linocut. In screen printing, the printing surface is a mesh stretched across a wooden frame. A stencil is applied to the mesh to seal the non printing areas and ink is scraped through the mesh to produce an image.
