The plate is first covered with an acid-resistant resinous substance. The artist then takes a finely pointed needle and draws the design out of this resinous ground. The drawing instrument does not cut into the metal surface. The image, to be printed, is represented by the areas in which the copper of the plate has been exposed. The plate is then immersed in an acid bath. The acid eats into the plate only in those areas not protected by the ground.