In 1979, Crayola crayons introduced a Wolfe Brown colour crayon. He had drawn directly on the walls using graphite, colored pencil, crayon, and chalk. Fixative is used to prevent pencil and crayon marks from smudging. See the List of Crayola crayon colors. It was continued as a Crayola crayon color until 1990. See the website "Lost Crayola Crayon Colors". The site theme is stylized with colorful hand-drawn crayon and colored marker. In 1990, "royal purple" was formulated as one of the Crayola crayon colors. The Sketch Book of Geoffrey Crayon, Gent. His primary drawing material has been the paintstick, a wax-like grease crayon. One American author makes an appearance, Washington Irving, under his pen name of Geoffrey Crayon. In the early 1970s he drew primarily with charcoal, and lithographic crayon on paper. "Friday" () and "Pastel Crayon" (). She also finds the purple crayon scratches inside the wheat bin. There was a tiny stamp in the corner drawn with a red crayon.