Shown above from left to right are sticks of soft vine, thin willow and compressed charcoal.
3/29/12
Charcoal from Philadelphia Museum of Art
As a stick of charcoal is applied to paper, it splinters and the almost weightless particles scatter lightly over the surface producing dusty gray passages and soft lines that even the gentlest rubbing can smudge or erase. These qualities have favored its use for preparatory drawings, rapid sketches, and underdrawings throughout the centuries. The photomicrograph at the left illustrates the sparkle of the minute fractured particles in a charcoal stroke as they reflect light. Found in prehistoric cave paintings and gaining substantial popularity in the nineteenth century, charcoal has been used by artists of all periods. Natural charcoal is made by slowly heating vines or wooden twigs in an airtight chamber, after which it can be used directly without the addition of binder. For denser, more saturated marks, the artist soaked the charcoal sticks in olive or linseed oil, a technique practically forgotten today. By the mid-nineteenth century, the need for darker charcoal was met commercially with compressed charcoal, which consists of charcoal powder pressed into sticks and fired in a kiln. A charcoal stroke can be easily manipulated or removed with a soft rubber eraser or smudged with a tight roll of paper called a “stump” or “tortillon.”
