The artist uses a mixture of black pigment and grease to draw the initial image onto the transfer paper or stone. The medium exists in different forms, which produce varying effects. In its solid form, there is the lithographic pencil, crayon or chalk which produces various thicknesses of lines and allows subtle tonal gradations. The ink can also be applied in liquid form, called a tusche. This has to be painted on with a brush and produces a fine, smooth surface. For Redon, the artist's materials were 'agents that ... collaborate with him, and also have something to tell in the fiction he will accomplish. The material reveals secrets, [and] it has its genius.' Redon engaged emotionally with the lithographic medium. Whereas he endows the stone with a difficult human temperament, he bestows intelligence on the ink.