What is lithography?

In lithography, the artist draws an image on a smooth block of limestone using a fat or oil-based medium, such as a grease crayon. After drawing the image, a mixture of acid and gum arabic is applied to the stone. This solution penetrates into the pores of the stone around the drawn image. The stone is dampened with water and inked with an oil-based ink—the areas treated with the acidic solution will attract the water, while the areas treated with grease will attract the ink. A sheet of paper is placed on the stone and then passed through a flat-bed press. If the chemical processing has been done correctly, the print will duplicate exactly the tonalities and textures drawn on the stone.