A lithograph is a print made by an artist on a press. Some lithographs are produced by machines today with photographic processes, but the original lithograph was made by drawing on a stone and printing from that same stone. Since the particular kind of stone may be hard to come by, some artists use the same process on a special lithographic plate made of metal.
Know how a lithograph is made. A true lithograph is created from a drawing made directly onto a stone or a treated metal plate. The artist draws on the stone or plate with a grease pencil or crayon, which is then is treated with fat or oil mixed with gum arabic, which will cause the lines drawn on the stone to attract the greasy printer's ink and the areas not drawn on to repel it. Then the stone or plate is treated with a turpentine or solvent that removes the drawing. But a "ghost" image of the drawing has been bonded by the first treatment to the plate or stone. It is dampened with water, and only the blank areas can absorb the water at this point, since the surface has been changed to receive water (the blank area), or to repel it (the drawn area). The stone or plate is inked, and only the area of the stone that has repelled the water takes the ink, leaving the "drawn" image inked. The stone or plate is then put on a printing press, a piece of wet paper is laid on it, padded, and a board laid on top of the paper and the plate or stone with paper on it is put under great pressure while going through the press, so that the damp paper receives the ink left on the stone.
If there is to be more than one color, registration marks on the original image will be closely matched; for a second color, the paper holding the original image will be placed on the stone or plate with the second color and run through the press again.
Check out the lithograph for sale with care. It may be something else other than lithograph, even though the seller is calling it a lithograph. The value or price of a lithograph depends on the quality of the art work, the quality of the paper and how successfully the print was made. The reputation of the artist who produced the print sometimes has a bearing on the price and so does the reason the print was made. Many lithographs were produced in order to inform the general public of how things looked before the camera was invented, and many of these series of illustrations are now quite valuable.
Look at the paper the print is on. It should have a watermark, with a name, such as "Arches." If the paper is old, it will have stains or discolorations from exposure to light or water, unless it has been perfectly preserved in an airtight, watertight container, such as a well-sealed frame with mat. These discolorations are not undesirable and show that the print is old. If you want a perfect print, old or new, you do not want any discolorations, but these perfect prints will cost quite a bit more, if they exist.
Look at the ink. Feel it, if you can. If the ink is raised, it is not a lithograph, it is an etching. If you are not allowed to touch it, look at it with a magnifying glass. If the ink is flat, it might be a lithograph.
Look at the gray areas with a magnifying glass. If there are tiny dots, it is a contemporary reproduction of a print. The small dots are called "Benday dots," which are created with a mechanical photographic process that separates the ink in gray areas so that it will not saturate the paper. If the area is filled in, it is probably a lithograph, as the lithographic process (either with stone or metal plate) creates a rather smooth, all-over gray area that would only have natural irregularities from the surface.
Look at the signature line. It should be signed with the name of an artist that can be researched. If the artist cannot be found, there is a probability that the name is made up, which would make the print suspect, as it may be mass-produced. The signature is usually done with a pencil.
Look at the number. This is called an edition number. The first number is the unique number for that particular print, and no other print has that number. The first print off the press is usually the Artist's Proof (AP), so there may be no number, but the letters "AP." The second print off the press is usually 001. The second number after the slash is the number of prints made in that edition in total. If it is a limited edition from the original stone or plate, it is usually 100. If this number is in the thousands, it is not a limited edition. These numbers are usually written in pencil.
There may be a title written in the center of the signature line. The number of the print is on the left, the signature of the artist is on the right, at the bottom of the print.
Follow the steps above, and if each item is verified (the paper, the ink, the artist's signature and the edition number), you may feel fairly confident you are looking at a real lithograph. It's value lies, as mentioned, in the quality of the drawing, the quality of the paper, the artist's reputation and the purpose of the illustration.
If any of the items listed are not as they should be on a lithographic print, ask for certification of its authenticity. The certification should tell if the print is a lithograph, a block print, an etching, a rotogravure or a seriograph (silk screen) print. Each of these kinds of prints are created with valid printmaking processes that involve the artist's hands-on participation, but they are not done with the same process as a lithograph print.
If a certification is not available for the lithograph, have the print examined by an artist/lithographer, who will be able to determine if it is a lithograph and how much it is worth. there are Internet sites that can tell you the prices of similar prints and there are art experts available in large cities, at auction houses, who can look at a print and tell you its market value.