Speaker 1: Welcome to Brainstuff from house stuff works dot com where
Speaker 1: smart happens. Hi am rc Brain with today's question, how
Speaker 1: do they get the lead in a wooden pencil? Take
Speaker 1: a look at the writing end of a brand new
Speaker 1: wooden pencil before sharpening it. It appears that the wood
Speaker 1: casing is one solid piece. This might lead you to
Speaker 1: believe that pencil makers bore a hole straight down the
Speaker 1: middle of the wood and then slide in a rod
Speaker 1: of lead. Although early pencils were constructed that way, it's
Speaker 1: not how most wooden pencils are mass produced today. More
Speaker 1: than fourteen billion pencils are produced in the world every year,
Speaker 1: enough to circle the Earth sixty two times. Before discussing
Speaker 1: how the lead is put into the wood casing, let's
Speaker 1: clear up what the lead actually is. Pencil lead is
Speaker 1: not lead at all. It's a combedyation of finely ground
Speaker 1: graphite and clay, mixed with water and pressed together at
Speaker 1: high temperatures into thin rods. We call it lead because
Speaker 1: the Englishman who first discovered graphite believed that they had
Speaker 1: found lad. According to the Cumberland Pencil Museum, in the
Speaker 1: mid sixteenth century, a violent storm knocked over several trees
Speaker 1: in England, uncovering a large deposit of a black substance
Speaker 1: that was first thought to be led. More than two
Speaker 1: hundred years later and English scientists discovered the substance was
Speaker 1: not actually led, but a type of carbon instead. The
Speaker 1: substance was named graphite, after the Greek word meaning to write,
Speaker 1: since that's how people used the substance. Early pencils were
Speaker 1: crude versions of today's standard model. The first pencil was
Speaker 1: a chunk of graphite used by carpenters to make markings
Speaker 1: without denning their materials. This evolved into a graphite chunk
Speaker 1: wrapped in sheepskin, followed by a ring wrap graphite pencil,
Speaker 1: the first pencil with a rod shaped graphite core. To
Speaker 1: use one of these pencils, the writer would have to
Speaker 1: unravel the string as the graphite wore down. The next
Speaker 1: major leap in design was hollowing out a stick of
Speaker 1: cedar and sticking a piece of graphite down the hole,
Speaker 1: an idea often credited to the Italians. The English embraced
Speaker 1: this idea but simplified the manufacturing process considerably. Instead of
Speaker 1: hollowing out a piece of wood, they simply cut a
Speaker 1: groove in the wood. Inserted a piece of graphite and
Speaker 1: broke it off level with the top of the groove.
Speaker 1: Then they glued a small slat on top, encasing the graphite. Today,
Speaker 1: most wooden pencils are mass produced from large blocks of
Speaker 1: cedar cut into slats. A machine cuts eight grooves half
Speaker 1: as deep as the graphite clay rod is thick into
Speaker 1: slats and then places rods in each groove. Once the
Speaker 1: rods are in place, a second groove slat is glued
Speaker 1: on top of the first. When the glue drives, the
Speaker 1: slats are fed through a cutting machine that cuts the
Speaker 1: wood into various shapes and divides the slats into eight
Speaker 1: separate pencils. The seams of the two slats are then
Speaker 1: sanded down and several coats of paint are applied to
Speaker 1: the pencil, giving it the appearance of a single solid structure.
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