Among the earliest known drawing materials, charcoal sticks are produced by burning vines or twigs of wood in an airless atmosphere. The black tonality of charcoal varies based on the type of vine or wood it is derived from. Composed of loosely bound, splinter-like particles that sit on the surface, charcoal marks are easily smudged or disrupted. Some artists exploit this quality by manipulating the marks with implements such as erasers, rolled paper stumps, or their fingers to create tonal effects. Charcoal crayons, developed in the 19th century, consist of charcoal powder compressed into sticks that produce a denser, darker mark.