The artist begins by drawing on the stone with a greasy lithographer's crayon, or with a more powerful medium called "tusche". Tusche can be brushed on like ink or applied with a pen for different effects. Lithography is unique among printmaking techniques in the way that it allows the artist to draw freely on the stone. Artists from a wide variety of media other than printmaking are drawn to lithography because of the directness of its process.
After the artist has completed his drawing, the stone is chemically treated to fix the image securely. The grease in the lithographer's crayon or tusche will repel water during the lithographic process. The unmarked, grease-free surface of the stone, on the other hand, will absorb water.
In the next step, the entire stone is cleaned with turpentine or a similar solvent. The artist's drawing is then no longer visible on the stone. The printmaker (normally the printing is not done by the artist himself) wipes the stone with a wet sponge prior to applying the ink. The portion of the stone's surface which absorbed the water from the sponge will repel the oil-based ink; the rest, which was marked with greasy crayon or tusche and thus repelled the water, will now accept and retain the ink. By this means, the artist makes the stone accept ink in places where it is desired, but reject ink in those spaces he or she wishes to remain empty white space.
The printmaker then uses a lithographic press to force the paper against the ink. Since lithography stones do not wear out like the copper plates used in etching, this process of wetting, inking and pressing the stone can be repeated many times. Along with this capability of producing multiple impressions, lithography excels at creating areas of vivid, solid color as well as subtle shading effects. Because of this, it has appealed to painters such as Toulouse-Lautrec, who turned to multicolor lithography to achieve a widely reproducible art. A separate stone must be produced for each color, and the paper then carefully aligned for the multiple pressings required to match up the different colors on the same printed sheet.