Drawing Techniques: a Guide
Dry Media: Charcoal  
Charcoal is made from wooden slips bound together and carbonized in an airtight container, so that they do not burn to ashes. What remains are friable sticks, which leave long, sharp-edged particles in the paper fiber, producing a line denser at the pressure point, but more diffused at the edges than black chalk, because of its friability. The overall result is less precise, ideally suited to freer figure studies and heads. It is also the most easily erased of media, making it ideally suitable for underdrawing.

Reference: Stratis, Harriet K., "A Technical Investigation of Odilon Redon's Pastels and Noirs," The Book and Paper Group Annual, 14 (1995)


  Odilon Redon. Untitled. Art Market
Oiled Charcoal