2. The background is cut away or eaten by acids, leaving the lines in relief as in wood engravings, half tones, and zinc plates.
3. There is no relief or depression, but the surface is smooth, as in lithographs.
In etchings and steel and copper plates the surface is usually covered with a waxy substance, or something which resists the action of acid. Then it is often smoked so that it will be easier to see the lines of the drawing which are made with fine steel tools, cutting through the wax to the surface of the metal. It is not the intention to cut the metal, but merely to scratch through the coat of wax to expose the metal. Then the plate is put in acid, and each line is eaten into a groove varying in depth according to how long it is left in the acid. If some of the lines are not deep enough, the rest of the plate may be covered with the waxy substance and it may be put in the acid many times until all lines are the desired depth.
A print is made from this plate by covering it with ink, allowing the ink to fill the grooves, and wiping the rest of the plate clean. Then paper is pressed upon it.
Rembrandt ranks first among etchers. Other well-known artists are Albrecht Dürer, Van Dyck, and James McNeill Whistler.
In wood engravings, half tones, and zinc plates the picture is either drawn or photographed upon the plate. Then the spaces between the lines are either cut away with the sharp steel tools of the engraver, which vary in shape and size, or, the lines being protected by the waxy substance, the surfaces between are eaten away by acid. Thus the original lines are raised higher than the rest of the plate. The raised lines are then inked and pressed against the paper. A wooden block may also be molded into a “metal cast” in order to preserve the engraving.
LITHOGRAPHY
“Lithography is the art of drawing or writing upon stone.” The best lithograph stone is found in Bavaria, and is usually cut from three to four inches thick, varying in size from six by eight inches to forty-four by sixty-four. The larger sizes are very rare. It is said that drawings may be removed and one stone used as many as two hundred times. Sometimes zinc or aluminum plates are used as a substitute.
The drawing must be reversed and should be drawn direct upon the stone, although transfer paper is sometimes used. The ink or crayon used is made of fatty substances, and when the drawing is complete the stone is bathed with a solution which fixes the lines permanently and gives them a greater attraction for fatty substances, such as printers’ ink. The spaces between the lines, however, do not attract the ink, so that when a roller of ink is passed over the stone, only the lines are affected. A piece of paper is then pressed upon the stones by the aid of the printing press, and every line of the drawing is reproduced.