A technique of acid-biting areas of tone rather than lines. A ground is used that is not completely impervious to acid, and a pebbly or granular texture (broad or fine) is produced on the metal plate. Stop-out and second and third bitings are used to produce variations of darkness.
In all intaglio prints except mezzotint the design is produced from ink in lines or areas below the surface of the plate. The smooth surface is wiped of ink before printing, though some ink may purposely be left on the plate for tonal effects. Considerable pressure is used in the press to force the ink out of the lines and areas and, to an extent, to force the paper into them, so the final printed image will appear to be slightly raised above the surface of the uninked paper.