LITHOGRAPHY

Lithography takes its name from the Greek words lithos meaning ‘stone’ and graphein ‘to write’. In its most primitive form, lithography would involve an image being etched into a smooth stone, ink would be applied to the stone, and paper pressed against the stone. The ink would transfer to the paper, absent only where the stone had been engraved. In the 18th century lithography used water with opposing substances like oil-based materials to achieve the desired disparate effect. Modern lithography employs the same basic principle but is much more efficient and is therefore used in the reproduction of most materials with graphics and print. A printing plate is covered with photosensitive emulsion before the photographic negative of an image is pressed against it and the plate is exposed to an ultraviolet light. Once developed, the emulsion shows a reverse of the negative image – an exact duplicate of the original (positive) image….

SCREEN PRINTING

Method in which ink is applied directly to the surface to be printed (substrate). The image to be printed is photographically transferred to a very fine fabric (the screen) such that the non-printing areas are blocked off and the fabric serves as a stencil. The ink is wiped across the screen to pass through the unblocked pores and reach the substrate. For each color to be printed a separate screen is prepared and the process is repeated. It is more suitable for curved shapes (such as bottles and cups), non-porous surfaces (such as ceramics and metals), and short print runs. Also called serigraphy.

ETCHING

This process uses acid to bite an image into a metal plate that is coated with an acid-resistant ground. A sharp needle is used to scratch the image through the ground, exposing the metal. The plate is then immersed in an acid bath where the drawn marks are etched. The characteristics of the marks produced depend on the tool used to draw the image, the type of ground coating the plate and the length of time the plate is etched in the acid bath. The etching processes are the most versatile of the intaglio techniques and are often used in combinations.

ENGRAVING

For this technique, a metal plate is incised with a tool called a burin. Great skill is required to manipulate the burin as it is pushed at different angles and degrees of pressure to produce a characteristic thin to thick line. Engraving techniques were used by the Greeks, Romans and Etruscans for decorating objects but were not used for printmaking until the mid 15th century in Germany. Engraved images are comprised of a multitude of crisp, fine lines. Shading is traditionally rendered by multiple parallel lines or cross-hatching.