Etching is a traditional printmaking medium which dates back to the time of Rembrandt. An image is drawn with an etching needle onto a metal plate which has been covered with a ground of wax or some other acid resistant material. The ground is removed by the needle, so that when the plate is immersed in a bath of diluted acid, only the drawn lines are etched. An aquatint tone is produced when the plate is covered with a fine coat of resin particles, which fuse to the metal when heated. The acid can only etch the areas between these fine particles, so a continuous tone is produced, which darkens the longer the plate is left in the acid.
In recent times less toxic chemicals such as ferric chloride and copper sulphate have been used to etch the metal. Drypoint is a completely non-toxic form of printmaking, as the lines are drawn directly into the metal and not etched. Rembrandt reworked many of his etchings with drypoint. Etching, aquatint and drypoint are intaglio techniques, that is, the ink is rubbed into the lines and wiped away from the surface, so that only the incised lines are printed. Intaglio plates can only be printed in an etching press.
Wood engraving also has a long history. Thomas Bewick, an eighteenth century English artist, was one of its greatest exponents. Only end grain wood is fine enough for this technique. Unlike etching, it is a relief process, i.e. the surface of the block is printed, and the ink is applied with a roller. Relief prints can be made by hand, using the fingers, a roller, a wooden spoon or a baren (a Japanese tool made from bamboo). Relief prints can also be made with a block printing press or an etching press, provided the block is not too thick.
Other relief media are linocuts, woodcuts and collagraphs, which are made by building up the surface of a plate with card, found objects and glue. (collagraphs can sometimes be printed using the intaglio technique, and it is also possible to print some etchings in relief).
Solarplate etching is a much less toxic form of etching. No chemical baths are necessary: the image is drawn on transparent material and exposed onto a photopolymer plate, either in the sunshine or in a UV box. The resultant etch is produced by first immersing the plate in water and gently scrubbing it, and then hardening it in the sunlight. An aquatint effect can be produced by exposing the plate to a random dot screen. It is also possible to produce solarplate relief prints that are as fine as wood engravings.
Monotypes are the simplest of all printmaking techniques. A metal or glass plate or a piece of acetate is rolled up with black or coloured ink, and an image is drawn into it with any hard tool, such as a brush handle or a palette knife. The ink can also be painted on with a brush, or wiped with a rag. The first impression is always the strongest, but a small number of ‘ghost’ prints can be produced, which can be developed further with other media such as pastels or paint. Edgar Degas used monotypes as the basis for many of his pastels.