Pencil lead is not lead at all; it's a combination of finely ground graphite and clay, mixed with water and pressed together at high temperatures into thin rods. We call it lead is because the Englishmen who first discovered graphite believed they had found lead.
Pencil lead is composed primarily of a carbon substance known as graphite. Graphite lead transfers easily to other objects with which it comes into contact. Marks from graphite pencil lead may be erasable on paper, but if you may wonder if they would ever come out of a surface like upholstery, walls or clothes, it can be easily wash off by water and soap.