This is a type of [engraving#MATERIALES#9] where the lines of the image are cut away. A copper plate is covered with a protective varnish. Afterwards a drawing is done on this ground with a needle without scratching the metal. The plate is then submerged in an acid solution which corrodes the exposed metal. Finally the plate's surface is covered with ink which is held in the furrows of the drawing. The surface is cleaned to remove any excess ink. A dampened sheet of paper is placed over the plate. A thin layer of rubber is placed on top of the paper and then the plate is rolled through the press. The pressure forces the paper into the crevices, absorbing the ink. The technique allows multiple high quality reproductions. Tonal gradations are subtle and the lines are very fine, which means a freer execution of images can be achieved than with woodcut.