A mechanical pencil, also clutch pencil, is a pencil with a replaceable and mechanically extendable solid pigment core called a "lead" . The lead, often made of graphite, is not bonded to the outer casing, and can be mechanically extended as its point is worn away as it is being used. The vast majority of mechanical pencils have erasers.
Other names include: microtip pencil, automatic pencil, drafting pencil, technical pencil, draughting pencil, click pencil (generally refers to a specific brand), pump pencil, leadholder, Pacer (Australian English, ca. the 1980s), propelling pencil (British and Australian English, often refers to higher-end mechanical pencils), pen pencil (Indian English), and lead pencil (Bangladeshi and American English).
Mechanical pencils are used to provide lines of constant width, without need of sharpening, for tasks such as technical drawing as well as for clean looking writing. They are also used for fine-art drawing. Since they do not have to be sharpened, they are also popular with students. Mechanical pencils were first used in the 18th century, with many designs patented in the 19th and 20th centuries.
History
Conrad Gesner described a lead holder pencil in 1565, but the lead had to be manually adjusted to sharpen it. The earliest extant example of a mechanical pencil was found aboard the wreckage of HMS Pandora, which sank in 1791.
The first patent for a refillable pencil with lead-propelling mechanism was issued to Sampson Mordan and John Isaac Hawkins in Britain in 1822. After buying out Hawkins' patent rights, Mordan entered into a business partnership with Gabriel Riddle from 1823 to 1837. The earliest Mordan pencils are thus hallmarked SMGR. After 1837, Mordan ended his partnership with Riddle and continued to manufacture pencils as "S. Mordan & Co". His company continued to manufacture pencils and a wide range of silver objects until World War II, when the factory was bombed.
Between 1822 and 1874, 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 0.9 mm lead was introduced in 1938, and later it was followed by 0.3, 0.5 and 0.7 sizes. Eventually, 1.3 and 1.4 mm mechanisms were available, and 0.4 and 0.2 versions are now produced.
The mechanical pencil became successful in Japan with some improvements in 1915 by Tokuji Hayakawa, a metalworker who had just finished his apprenticeship. It was introduced as the "Ever-Ready Sharp Pencil". Success was not immediate since the metal shaft—essential for the pencil's long life—was unfamiliar to users. The Ever-Ready Sharp began selling in huge numbers after a company from Tokyo and Osaka made large orders. Later, Tokuji Hayakawa's company got its name from that pencil: Sharp.
At nearly the same time in the US, Charles R. Keeran was developing a similar pencil that would be the precursor of most of today's pencils. Keeran's design was ratchet-based, whereas Hayakawa's was screw-based. These two development histories – Hayakawa and Keeran – are often mistakenly combined into one. Keeran patented his lead pencil in 1915 and soon afterwards arranged production. After some improvements, his design was marketed as the "Eversharp" pencil by the Wahl Adding Machine Company; by the early 1920s, Wahl had sold more than 12,000,000 Eversharps.
Some of the manufacturers are: Pentel, Pilot, Tombow, Uni-ball and Zebra of Japan; Faber-Castell, Lamy, Rotring and Staedtler of Germany; Koh-i-Noor Hardtmuth of the Czech Republic; Bic of France; Monami of South Korea; PaperMate and Parker of USA; Caran d'Ache of Switzerland and numerous Chinese as well as other Asian and European manufacturers.
Mechanism types
Mechanical pencils can be divided into two basic types: those that both hold the lead and can actively propel it forward, and those that only hold the lead in position.
Screw-based pencils advance the lead by twisting a screw, which moves a slider down the barrel of the pencil. This was the most common type in the earlier part of the twentieth century. Many of these have a one-way locking mechanism to allow the lead to be pushed back into the pencil.