ETCHING

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 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.

AQUATINT

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.

SCREEN PRINT

The screen printing process uses a porous mesh screen made of fabric or stainless steel stretched tightly over a frame made of wood or metal. A stencil is produced on the screen either manually or photochemically to define the image to be printed. Ink is then forced through the fine mesh openings using a squeegee that is drawn across the screen. Ink will pass through only in areas where no stencil is applied, thus forming an image on the page.

LITHOGRAPHY

Invented in the 1796, using limestone, the surface is prepared so that the image takes the ink, while the non-image areas repel it. The inked image is transferred to paper by pressure using a lithographic press. Colour lithography arrived in 1837, using a separate stone for each colour. For example, theatre posters of the 1940s.

RELIEF PRINTING

Relief printing is where the areas around the image to be printed are cut away, leaving the image on the block in relief. The raised areas are then inked and transferred onto a second surface, usually paper. For example woodcut, lino cut and wood engraving.

INTAGLIO

Intaglio describes any printmaking technique in which the image is produced by incising into the printing plate – the incised line or area holds the ink and creates the image. This is the opposite to relief printing, in that the printing is done from ink that is below the surface of the plate. Print makers generally use either copper or zinc.