Lithography is a difficult and temperamental print medium that uses grease crayons to create images on polished limestone. The images are then chemically treated to bond with the surface of the stone to form a pattern, or matrix, on the stone. This matrix is then inked with a leather roller and the image is transferred to the printing paper with a litho press, which exerts tremendous pressure on the paper and stone. For a more complete explanation of the process, click on the "about litho" link.
Well printed lithographs have a wide tonal range and a delicate grain that is very similar to a pencil or ink drawing. Poorly printed lithographs look grainy, dirty, spotted or very dark and coarse.