Most people could not afford to own an original piece of artwork by Picasso or Van Gogh, but having a copy of their masterworks wouldn't be such a bad idea. This is where the idea of a lithograph comes into play. A lithograph is an authorized copy of an original work created by the artist himself or other skilled craftsmen. A lithograph is rarely worth more than the original artwork it reproduces, but if the print quality is excellent and the production numbers are low, it may still have significant value in the art world.

The printing process which creates a lithograph is different from other traditional methods. Most printing presses require the printmaker to etch an image or text into metal plates or physically carve out the image on blocks of wood or other soft material. To create a lithograph, however, no etching is required. The artist uses a set of greasy crayons or pencils to draw a mirrored image of the original artwork onto a smooth stone tablet. This is by far the most time-consuming part of the lithograph process.

After the image has been recreated to the satisfaction of the original artist or other authority, it is ready to be turned into a lithograph. The lithographic process hinges on the principle that oil and water cannot mix. An oil-based variety of ink is applied directly to the plate and immediately bonds with the equally greasy crayon lines. Water is then wiped onto the remaining unpainted areas to discourage the ink from smearing. A sheet of paper, preferably one with a high cotton content, is then placed over the entire plate.

The inked stone or metal plate and the paper are placed in a press and light pressure is used to transfer some of the ink. If the original image were a monochrome pen and ink drawing, this would be the only press run necessary. A color lithograph of an elaborate Van Gogh painting, however, might require several different runs with up to four different color inks -- black, red, yellow and blue. The same paper would be placed precisely over the re-inked plates, eventually creating a satisfactory lithograph copy. This same process is used to create color pages in newspapers.

Since the process for creating a lithograph can be just as time-consuming and detailed as an original painting, printing runs are often kept low to preserve value. A signed lithograph may have a set of numbers expressed as a fraction on one corner, such as 12/300. This means that the lithograph was the twelfth one produced in a series limited to three hundred prints. Some famous artists, notably Salvador Dali and Pablo Picasso, were more than willing to authorize or create numerous lithographs during their lifetimes. Others are not always eager to see their work reproduced on a commercial scale, making it more difficult to find authorized lithographs from them.

There are other ways of duplicating original artwork for the commercial market, so never assume the Monet print in an art store is indeed a lithograph. Ask the proprietor to confirm the printing method used to recreate your favorite piece of artwork. A signed lithograph may have more collectible value, but the print quality itself can be variable. When it comes to buying art, it is most important to buy what you like, regardless of the printing method.