One of the most important methods of intaglio engraving. It consists in laying an acid-resistant ground over a metal plate (copper is the best, Zinc is also used) on the surface of which the design is drawn so as to expose the metal. The plate is then bitten with a mordant, usually nitric acid (hence the term “eau-forte” in French),which incises the lines so that the plate can be inked and printed as an ordinary intaglio engraving.
The distinguishing characteristic of the technique is that it allows the designer much greater freedom of expression than other methods of intaglio engraving, since the laborious task of incising the plate manually is dispensed with. It has therefore been the preferred medium of artists who are primarily painters or draughtsmen. It does, however, require a certain technical experience to achieve good results, particularly in laying the ground and biting the plate.
An etching is executed in five stages:
(1) The plate is polished and cleaned with chalk or whitening to ensure that the ground adheres well.
(2) Laying the ground: either a ball of solid ground is melted over the plate, or a cold liquid ground is used. The former remains soft for a longer period, the latter dries rapidly and must consequently be worked more quickly than a hard ground. Different grounds are used for reworking the plate.
(3) The design is cut through the ground with an etching needle; the lines must remain separate in order to avoid foul-biting.
(4) The plate is then bitten (or “etched”) either by placing it in an acid bath or by covering it with the mordant.
(5) The ground is removed before the plate is inked and put through the press like an ordinary intaglio engraving. The etching process is an inherent part of various other techniques, e.g. aquatint, brush etching, soft-ground etching, sugar-lift process, etc. lt can also be combined with burin engraving and drypoint where the etched part of the design is done first.
See: biting, grounds and varnishes, impression, intaglio, techniques.
The etching process must not be confused with the “ etch” used in lithography: this is a gum acid solution applied to the stone (already drawn and prepared with a resist) with the aim of reinforcing the image.
See: reinforcing (the lithographic image).
Lightly etched (plate). One which has been etched for a short period. An impression taken from such a plate is light in tone. A ‘light etch” refers to a weak acid or any diluted mordant.
Etching a la plume”. A method of intaglio printing in which a pen and ink drawing is made on a clean metal plate. When this has dried, the entire surface is covered with a light aquatint ground and placed in an acid bath Which has the effect of removing the ground Where it is to be found over the ink. The plate can then be bitten as for a normal etching. The technique is difficult to do Well, and was much improved by the sugar-lift process.