Lithography is a method of printing based on the principle that oil and water do not mix.

A lithograph print is made from an image which has been applied to a flat surface. Printing is done from a stone (lithographic limestone) or a metal plate with a grained surface; using oil based inks. The artist works on a separate stone or plate for each colour. Traditionally this was specially prepared limestone, but today both grained aluminium-printing plates and the original stones are used. An image is drawn or painted onto the stone or plate using a greasy medium. Litho pencils are waxy and range in hardness from 0, which almost melts in your hand, to 7, which is brittle. From the artist's standpoint, the drawing process is extremely natural because there is not a tremendous difference between drawing/painting on the stone and doing the same on a piece of paper. As the tusche dries, it reticulates. Net-like marks are left on the stone and show up in the print. This is a characteristic look unique to limestone lithography.  There are a few things to keep in mind, however:. Erasing a mistake is difficult, and a large mistake means starting over. Because there is little or no way to correct a mistake, the artist has to be willing to draw quickly and some can create their entire work in an hour or so. Others spend days at a stone. The printmaker must then ink, align and press the paper on these separate stones to create the final image. This oily image will repel water and accept the lithographic inks which are oil based. The plate is placed on a special press and rolled up with either leather or rubber rollers. Paper is placed on the print and

is run through the press by hand, one colour at a time. Usually one colour is printed per day, so the ink can dry. Thus a print that is built up of ten colours could take up to 10 days to edition.The printmaker must then ink, align and press the paper on these separate stones to create the final image. The chemicals used in processing are relatively harmless and pose no threat to the artist. Offset lithography, although evolving from the same chemical processes as hand lithography, is a separate and distinctly different process. Offset printing is the technique used in industry for printing books, magazines etc. It needs complicated machinery and equipment and is only used by artists to do reproductions of their work. When buying prints one should be aware that dealers and artists often refer to prints as original lithographs when they are in fact reproductions of artwork that are printed in the same way that posters and magazines are printed. These prints are not handprinted and they usually involve none or very little collaboration between the printer and the artist. They are often printed with inferior inks on inferior paper and will not have much of an investment value. When buying prints from someone you do not know well, it is always a good idea to ask for a copy of the documentation sheet. The documentation sheet will provide you with all the information that you will need to assure you of the integrity of the print that you are investing in. For more about lithography, watch these: youtube.com/watch?v=F1OqTvdWbUQ

https://www.youtube.com/watch?v=gWhb_HoWo-o

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