Lithography

Invented in Germany in 1798, lithography is perhaps best known from the prints of artists of the 1890s such as Toulouse Lautrec. Lithography is based on the chemical principle that oil (or grease) and water don't mix. On a special type of stone that has been cut-polished (or porous metal), the image is drawn with a greasy crayon or with a brush and specially prepared oil based ink. Using a sponge, the surface is then dampened with water. An ink charged roller (oil based) is then passed over the surface. Ink is accepted by the greased image and simultaneously repelled by the indrawn areas of the stone, which retain water. A print is obtained by placing a sheet of paper on the inked stone or metal which sits on the bed of a lithographic press and then running the stone and paper under the scraping pressure of the press. Linear and tonal values of great range and subtlety characterise lithographs because of the freedom possible when making the original drawing on the plate.

Arthur Boyd' s "White Cockatoo" Lithograph with Hand-drawn zinc plates

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