A mechanical pencil or lead pencil (usually called propelling pencil in British English, other names include clutch pencil, or Pacer after a Papermate model, a genericized trademark) is a pencil containing an internal mechanism which pushes ("propels") the thin graphite lead through the tip. Most models also have a rubber eraser on the end.

The mechanical pencil was first patented in Britain in 1822 by Sampson Mordan and John Isaac Hawkins. Between 1820 and 1873, more than 160 patents were registered pertaining to a variety of improvements to mechanical pencils. The first spring-loaded mechanical pencil was patented in 1877 and a twist-feed mechanism was developed in 1895. The 0.9mm lead was introduced in 1938, and later it was followed by 0.7mm, 0.5mm and 0.3mm versions.

The mechanical pencil became successful in Japan with some ameliorations in 1915 by Tokuji Hayakawa, a metal worker who had just finished his apprenticeship. It was introduced as the Ever-Sharp Pencil. Success was not immediate, since the metal shaft — essential for the pencil's long life — was unfamiliar to users. The Ever-Sharp began selling in huge numbers, however, after a large company from Yokohama made a large order. Later Tokuji Hayakawa's company got its name from that pencil: Sharp. Likewise to the name Ever-Sharp, mechanical pencils are used for their preciseness and the fact that they do not get dull.

A number of different types exist:

• Ratchet-based pencils, in which the lead is advanced by a button on either the end or the side. This button pushes three small pieces within the cap forward out of a ring holding them together. This separates those three pieces, allowing lead to go through between those.
• Screw-based pencils, in which the lead is advanced by twisting a screw, which moves a slider down the barrel of the pencil.
• Screw-based pencils in which the lead is advanced by friction with the screw.
• Twist-based pencils, in which the lead advances upon twisting the head of the pencil. Many of these will have a locking mechanism one way to allow the lead to be pushed back into the pencil.

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

Manufacturers

• Lamy
• Papermate
• Rotring
• Pentel
• Bic
• Zebra

References

• Deborah Crosby, Victorian Pencils: Tools to Jewels, Schiffer Publishing Ltd., Atglen, PA, 1998.

Pencils Writing instruments

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