Technique in cable, where the ink is deposited in the grooves and cavities obtained by the engraver with the help of one or more acid biting (formerly called aqua fortis). The plate, preferably of copper or zinc, is first covered with a layer on which the acid does not stick. This layer is a paint, usually composed of beeswax, resin and bitumen, warmed on the plate to make it uniform. Then proceed to draw the drawings on the paint, removing it with a tip up to the metal below. To facilitate the design you can also blacken the surface with the smoke of a candle or a wick soaked in oil, which is also useful to dry the paint faster. The matrix is then immersed in acid: the acid penetrates only where the protective varnish has been removed. The individual parts of the drawing can be subjected to different biting times, depending on the desired groove depth. If you do not want to be affected by the acid of the marks, they can be covered, by brush, with a protective varnish.
When the bites are done, you ink the plate after removing the protective varnish. Printing takes place with the use of moistened sheets of paper: pressed by the press, the paper enters the grooves of the matrix and absorbs the ink.