Natural charcoal sticks are the oldest sketching and drawing material in the world. The greyish-blue shade glides softly across the paper, rubs and smudges easily, and can be erased without difficulty and repeatedly overlaid. Their blueish hue has always held a fascination, even with the old masters. The charcoal pencils leave a much blacker line. Compressed charcoal with soot and clay give the charcoal pencils their deep black colour and can be produced in different degree of hardness.PITT charcoal pencil in supreme artist qualityGrease and oil freeDeepest blackDegree of hardness: hard