Mechanical pencil - Definition

A Mechanical Pencil is a pencil that does not need to be sharpened due to an internal mechanism that pushes graphite through the tip. It was first patented in Britain in 1822 by Sampson Mordan and John Isaac Hawkins. It has also been referred to as a "propelling" pencil due to the way graphite is pushed out through its tip. Most models have a rubber eraser on the end.

A number of different types exist:

• Ratchet-based pencils where the lead is advanced by a button on either the end or the side.
• Screw-based pencils where the lead is advanced by twisting a screw, which moves a slider down the barrel of the pencil.
• Screw-based pencils where the lead is advanced by friction with the screw.

Most mechanical pencils can be refilled with more graphite but some less-expensive models, especially screw-based designs, are disposable.

Mechanical pencils are considered to be more environmentally-friendly than conventional pencils due to the fact that wood is not necessary for its manufacture and no wasteful wood shavings are created.