An etching is a method used in intaglio printing. The top side of a copper or zinc plate is first coated in resin or wax layer. A sharp tool called a burin is used to draw into the plate. The resin layer helps to protect the area of the plate that is not being drawn into. The plate is then put into an acid bath. Usually nitric acid is used, though various materials have been used. The longer the plate is in the bath, the deeper the lines will be etched. After removing the plate from the acid, the plate is washed and the resin or wax layer is removed from the plate. Ink is then applied to the plate, sinking into the etched lines. An oil-free cloth is then used to remove all excess ink. Leaving more or less ink on the plate can create plate tone. Once the plate is ready, it is placed on the bed of the printing press. A damp printing paper is registered, placed over the plate and run through the press. The more pressure used, the darker the print will be.