What is Lithography? Lithography is a method of printing images from a stone surface, called a "plate."  Traditionally these stones are made of limestone. Sometimes a fine marble can be used, or ground glass, or anodized aluminum plates.  Once the stone plate is faced, ground and prepared by hand, the image is drawn directly onto the stone surface.  The image is then chemically processed to "fix" the drawing and prepare it for printing.  Light and dark areas of the image take on either ink or water and the ink is then rolled onto the stone and from there pressed directly onto paper.  Images can be produced from one color plate; or many color plates of transparent inks can be combined for each print.  Usually each color is printed separately on its own plate. The process of lithography is based on the aversion of oil and water.  The simplicity of the process makes it attractive to artists for the creation of fine art.  The same chemical principles at work in lithographic printing from stone has been adopted in modern forms of printing – offset printing and indigo printing all utilize the aversion of water and oil to reproduce images.  What is needed in a successful lithographic stone is the ability to hold either oil or water.  The chemical that best has this property is calcium carbonate (limestone). Lithographs printed from stone have a surface quality derived from the texture or "grain" of the ground stone surface.  This grained-surface is considered aesthetically pleasing by artists and collectors because of it's random, "living" dot texture.  Aluminum plates can be ground to have a surface similar to that of stone, and can be processed for printing, but it's surface doesn't match the natural quality of a limestone surface. Where do Lithographic stones come from? Once upon a time, eons ago, the planet earth was covered with an atmosphere of carbon gases. There was no terrestrial life because of the hot, poisonous gases.  Where did the gases go?  Things living in the oceans consumed these gases and locked them up into the earth itself.  Sea-plants and creatures absorbed carbon into their bodies and over time the remains of these plants and animals turned into great beds of coal, oil, natural gas, and limestone.  There was a wide variety of small sea animals, including many that do not exist today.  These animals lived and died in the oceans.  As they lived they built carbon into their bones – in the form of calcium carbonate.  Over millions of years the bones collected as the animals died.  So many animals lived and died that literally mountains of their bones have been left behind, and the atmosphere of earth now has much less carbon-gases.  Over eons of time these fossil bones were compressed to form into limestone - which, if compressed further can become marble.  If you go into the mountains you can often find fossils of sea animals from long ago.  Among these mountains of animal bones art the Pyrenees, the Alleghenies, mountains of China, and the Bavarian Alps. Most of the best lithographic stones have traditionally come from the Bavarian Alps.  A hard limestone with an even grain is best for printmaking - intact fossils are a flaw in a stone that can show in the drawing. Once the stone is mined, it is roughly shaped into thick, heavy rectangle slabs and the surface is planed evenly and ground smoothly to an even surface.  The artist then draws on the stone surface with any greasy medium.  After the artist has drawn the image, the stone is chemically fixed, and the prepared stone is moved to the printing press for printing.  After the image has been printed, the surface of the stone can be reground and the stone reused for a new image.  Most lithographic editions are small - if printed by the artist, only a few prints might be pulled from the stone.  Larger print houses may print larger editions - two hundred or more is a lot of prints to be pulled by hand. Lithography once was one of the most common methods of printing images, and in the 19th century it was widely used to produce and disseminate popular images to a newly democratic public. With the advent of photomechanical printing processes, around 1908, lithographic printing went into decline. A renaissance in lithography as an art medium occurred in the 1960's and '70s. Often photomechanical posters are sold today in cheap frameshops as "lithographs". If you look closely, you can easily tell a true lithograph from a photomechanical poster; just look closely at the little dots of ink. If the dots line up neatly in straight rows, it's only a mere poster. If the dots are random and grainy, most likely, you are looking at a true lithograph.