Hard ground etching
Hard ground etching is the indirect technique par excellence of intaglio engraving. It consists in applying a wax-based protective varnish on a metal plate -normally copper or zinc- which, once dry, is drawn on with a metal point. Subsequently, the fully drawn plate is introduced in a bath of acid or mordant, in such a way that the lines opened by the point in the varnish allow the acid to bite the metal. The operating time of the acid determines the lower or higher intensity of the bite of the strokes. For this, areas that require little intensity are covered with varnish shortly after the acid acts, while areas where a greater depth is needed are submerged again until the desired effect is achieved.