Which of the following is used in pencils ?
Nomenclature of pencil are done by H-B and Numeric basis. HB (“H” beckon hardness, “B” beckon blackness.) are two “Graphite” grading scale used to measure the hardness of pencil’s graphite core. Initially pencil were used a raw pieces of “Graphite” dug from the earth. Now Graphite is partially transformed to make pencils more durable, hard and bright marking.