LithographLithography is a method of printing invented by Alois Senefelder in 1798.
It is based on the antipathy of water and grease. The desired design is drawn with a greasy chalk on to a thick slab of stone. The stone is then wetted, and the water covers only the areas where there is no grease. A greasy ink is then applied to the stone with a roller; the ink is attracted to the already greasy areas, but does not adhere to the wet ones. Paper is then applied to the slab and the design which is now inked is transferred to it.
Artists such as Goya, Daumier and Manet were accomplished lithographers.
The National Gallery, Trafalgar Square, London WC2N 5DN