The etching process dates from the 16th century, and no photographic aids are used. The artist draws through a resin resist (which is impervious to acid) on to a copper, zinc or aluminium plate with an etching needle. The plate is then immersed in acid so that it is etched along the needle lines. This etched linear drawing provides the foundation for all plates. The plates are then inked up and hand printed on to acid-free paper through an old intaglio press.
Another intaglio process using acid, in which the plate is carefully and evenly covered with a powdered resin dust and heated, so that each particle of dust becomes crystallised and adheres firmly to the plate. The particles leave small exposed sections of the plate, which are then bitten by immersion in acids. Through a series of resin treatments delicate gradations of tone can be produced. The aquatint is characterised by a fine or coarse grainy texture of tones.