Pastel

Pastel is an artists' medium of chalk and pigment, tempered with weak gum water and usually molded in the form of sticks; also a work done in this medium.  Pastel was in use in Italy in the 15th century and is doubtlessly much older.  It was introduced into 18th-century France by the Venetian artist Rosalba Carriera. The medium was then used by such masters as Maurice Quentin de La Tour and Vigée-Lebrun, and in the 19th century by Degas, Manet, Toulouse-Lautrec, Whistler, and Cassatt. In the 20th century Matisse was a master of pastel. Pastels are often classified as paintings, although the medium lends itself to the more direct and spontaneous approach of drawing.

Pastel sticks or crayons consist of pure powdered pigment combined with an inert binder.  The exact composition and characteristics of an individual pastel stick depends on the type of pastel and the type and amount of binder used.  Dry pastels have historically used binders such as gum arabic.  Methyl cellulose was introduced as a binder in the 20th century.  Often a chalk or gypsum component is present.  They are available in varying degrees of hardness.  Pastel media is available in the following forms: soft pastel, hard pastel, pastel pencil, and oil pastel.