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Lithography
After the drawing is completed, the stone is washed with a solution of nitric acid and gum arabic. This process, called "etching" the stone, produces a chemical separation between printing (image) and non-printing (non-image) areas. The grease from the crayon or tusche is liberated into the pores of the stone and the non-printing areas become desensitized, so that they do not attract grease. When the stone is to be printed, it is first washed with water. The non-printing areas attract and retain a film of water; the greasy areas repel the water. Printing ink is then applied to the stone with a roller. Previous Page | Next Page 2/3 |
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