Video on MoMA site about how lithographic prints are achieved: http://www.moma.org/explore/multimedia/videos/151/939
The process is lengthy and involved many deliberate steps including drawing the original artwork on a prepared limestone bock using certain drawing materials. Interesting that the material used to draw is not the material that is used to print – this is an etching method, so that the print is done using ink that is introduced during the preparation. The artist uses the properties of the oily media to create their image.
Inveted in 1797 by Alois Senefelder (Wigan, 2009, P139)