A process of Intaglio printing developed after 1513 whereby a copper
plate is heated and covered with a film of wax. As it hardens it forms
a Ground over the surface of the plate, which is impervious to acid.
The artist then exposes the copper by drawing an image, through the
wax coating, with the use of a needle. The plate is then immersed into
a bath of Nitric acid which etches or bites the exposed areas of copper;
the process could be repeated numerous times, with new lines being added
to create variable depth or a tonal effect.
The longer the plate is exposed to the acid the deeper & broader
the lines; when printed these lines will appear darker.
Graduation of tone could also be achieved by stopping out certain areas
of the plate, by removing it from the acid, cleaning it and covering
the exposed area to be stopped out with varnish. When reintroduced into
the acid the stopped out area would cease to be bitten, but the remainder
of the exposed lines would continue to be etched. A close inspection
of the lines will show that they tend to have a squared end as opposed
to the tapered end of an engraving.
The freedom of expression in the drawing made etching a popular medium
When etched to the artists satisfaction the plate was removed from the
acid, cleaned and inked. The ink could be wiped clean from all but the
etched lines, or to create a richer tonal effect, a feather or cloth
was employed to drag a tiny amount of ink from the etched lines to the
plate surface; the effect being known as Retroussage.
Etching was frequently combined with Drypont on a plate in order to
empathize particular detail.