Lead to that of primary lead; some refining processes may be skipped depending on the material recycled and its potential contamination. Of the sources of lead for recycling, lead–acid batteries are the most important; lead pipe, sheet, and cable sheathing are also significant. Contrary to popular belief, pencil leads in wooden pencils have never been made from lead. When the pencil originated as a wrapped graphite writing tool, the particular type of graphite used was named "plumbago" (literally, "act for lead" or "lead mockup"). Lead metal has several useful mechanical properties, including high density, low melting point, ductility, and relative inertness.
Mechanical pencil 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