Pencil Drawing

Pencils graded using this system are used to measure the hardness and resistance of varnishes and paints. The resistance of a coating (also known as its pencil hardness) is determined as the grade of the hardest pencil that does not mark the coating when pressed firmly against it at a 45 degree angle.
Another common method uses numbers to designate the grade of a pencil. It was originally created by Conté and adopted in the United States by John Thoreau, father of Henry Thoreau, in the 19th century. The following table shows approximate equivalences between the different systems: