One of the most basic drawing materials, known since antiquity. It is usually made of thin peeled willow twigs which are heated without the presence of oxygen. This produces black crumbly sticks, which leave microscopic sharp-edged particles in the paper or textile fibres, producing a line denser at the pressure point, but more diffuse at the edges. The overall result is less precise than hard graphite pencils, suited to freer studies. Charcoal smudges easily and is often protected with a sprayed fixative. It is used to make both sketches and finished works, and as under-drawing for paintings. In the twentieth century a processed version was developed, called compressed charcoal.