Lithography is based on the chemical process that grease and water repel each other. A greasy medium is used to draw on a prepared lithographic printing surface, such as limestone. The surface is dampened with water, which settles in the unmarked areas and is rejected by the greasy medium. The surface is then rolled over with printing ink, which adheres to the drawn marks. The ink is transferred to a sheet of paper by running the paper and the printing surface through a press. With this process, designs rest on the surface and are printed in reverse. Lithography was developed in the 18th century by Aloys Senefelder.