The foil or metal surface is coated with a varnish very thin but resistant to acid, on which the artist draws with steel spikes, leaving with his traces the metal bared. Then the plate is immersed in a nitric acid solution, which records the lines left by the bare metal. Finally the plate is washed with water and the varnish is removed with benzine so that it is ready for printing.
The metal surface is covered with powdered resin that is adhered to it by heat. Then, as in the etching, is engraved in acid, which attacks the copper plate in places not protected by the resin. The result will be a dotted drawing on black or brown background obtained through chinese ink, sepia or bistro.
Using a burin, the drawing is recorded on a square or rectangular block of boxwood.
Buring engraving: The drawing is engraved directly on the metal plate with steel spikes and burins as those used for engraving wood, without the intervention of any acid.
Soft varnish engraving: Metal engraving obtained by a process similar to etching, but using a soft mordant bath. After the metal plate is coated with a thin layer of tallow, one or more sheets of paper are placed upon it and the drawing is done in pencil on them. The metal is exposed in the drawn parts, that are attacked by mordant into a fairly long bath. The resulting engraving gives the appearance of a pencil drawing. It achieves good results when combined with aquatint.