Hello, this is the technical process description in Art Fundamental (by Ocvirk, Stinson, Wigg, Bone, Cayton, 154). Hope it helps:
In lithography , a full range of achromatic value is drawn by oil crayon on limestone (or metal plates). After being chemically treated and washed in water, the stone allows the application of ink only in the drawn areas. When the ink stone is covered with paper and passed through a press with a scraper bar, the pressure of the press forces the ink to transfer to the paper.