Glossary of Printmaking Techniques
Also referred to as planography or surface printing, lithography operates on the principle that water and grease repel each other. The image is created on a matrix of limestone, with a grease pencil, crayon, or liquid (tusche). The stone is washed with a solution of nitric acid and gum arabic, which affects the surface chemically so that the greased areas (the drawing) are etched onto the stone, but the non-greased/non-printing areas are unaffected. When the stone is then dampened, and a grease-based ink rolled onto the surface, the ink will adhere only to the already greasy areas. Paper is laid on the stone, subjected to a press, and the image on the stone is transferred to the paper.
The name is derived from the Italian tagliare, meaning "to carve." Intaglio is also referred to as cavo relievo (reverse relief). Intaglio involves engraving or etching on a zinc or copper plate, by means of incising a drawing out of the surface, and thus creating a kind of relief in reverse. The matrix/plate is inked, and then rubbed clean so that the only ink remaining is that in the furrows carved by the etching process. A dampened paper is laid on the plate, and the two are rolled through a heavy press. The paper is forced into the recessed design, and so the drawing is transferred. Etching, aquatint, and mezzotint are intaglio methods.
A form of intaglio, "etching" is often used synonymously with "intaglio." A metal plate (zinc or copper) is covered with an acid-resistant ground, on which a design is scratched with a variety of sharp tools. The plate is then immersed in an acid bath, and the acid eats away (bites, etches) the areas exposed where the resinous ground has been scratched away. The longer a plate has been left in the acid, the deeper and hence darker the etched areas become. The plate may be inked and impressions pulled from it, as above.
Technically, aquatint is a form of etching, using tonal values instead of lines. The plate is lightly coated with a powdered porous ground (such as finely-powdered resin, or spray paint), through which the acid bites, to give tonal effects like ink or water colour washes. To allow for varying degrees of darkness, areas may be "stopped-out" with an acid resistant varnish at any stage of the etching, and the time may be varied in which areas of the plate are exposed to the acid. Aquatint is generally used in conjunction with etching.
A plate is roughened with a network of small burred dots, applied by a toothed "rocker", and which, if printed, would produce a rich black. To achieve tonal variations, up to white, the plate is scratched and brushed to various degrees, to determine how much ink is accepted. To smoother the surface, the less receptive it is to ink. It is inked and printed as above.
Drypoint is often used in conjunction with etching. It consists simply of drawing on a metal plate with a sharp graver. The burr left by the furrowed metal catches the ink and yields a rich printed line. Because of the fragility of the burr, plates with drypoint details cannot bear very many impressions.
Relief is the opposite in principle to intaglio. The image is drawn on the block or plate, and all else is carved or gouged out from around it, so that the drawing stands out in relief. The drawing presents the surface which is inked, then. As opposed to intaglio, the recessed areas print white.
Silkscreen or Serigraphy
Literally "writing on silk," serigraphy also is the favoured method of commercial or mass print production. Based on stencil techniques, it involves a masking of a fabric screen either by a paper stencil or a glue sizing. Through the screen areas left open (unmasked) ink or paint is applied, to a sheet of paper below. Silk screening does not require a press.