Believe it or not . . .
There's no lead in pencil lead!
The center of the pencil -- known as the writing core -- is made of a non-toxic mineral called graphite.
Click here, if you are looking for more information on the safety of pencils with respect to lead content.
Early Graphite Use.
Graphite came into widespread use during the 16th century, following the discovery of a large graphite deposit in Borrowdale, England. As the story goes, a passerby found bits of shiny, black graphite clinging to the roots of a fallen tree. The whole countryside was abuzz with talk about this mysterious mineral, which soon came to be known as "plumbagoi" or, more commonly, "Blacklead."
Graphite leaves a dark mark, making it ideal for use by writers and artists. But it was so soft and brittle that it required a holder. At first, sticks of graphite were wrapped in string. Later, the graphite was inserted into wooden sticks. These initial pencils actually used hand cut slivers of gaphite inserted into a rectangular shaped groove in the pencil barrel. The wood-cased pencil was born.
In 1795, a French chemist named Nicholas Jacques Conté patented a new process for making graphite pencil leads. This method mixed powdered grahite and clay in a water slurry, then formed sticks which were hardened in a kiln. These composite graphite-clay leads allowed for more efficient use of graphite and revolutionized the pencil industry. Not only did it reduce cost of the leads, but by adjusting the ratio of clay and graphite powder in the formula the changing hardness of the lead allowed more control of the lightness and darkness of the graphite mark left on the paper.
Graphite in America.
In 1821, Charles Dunbar (the brother-in-law of author Henry David Thoreau) discovered a graphite deposit in New England. This graphite was of a quality superior to any previously found in the United States, though not typically up to the European quality. With this higher quality material for its writing cores, the US pencil industry began to develop in New England close to these graphite deposits, and the Thoreau pencil factory came to be known as one of the finest makers of pencils in America.
Graphite in Siberia.
While searching for gold in the streams of Siberia, French merchant Jean Pierre Alibert came upon some very round, very smooth pieces of pure graphite. Reasoning that they must have been carried a long distance downstream, Alibert trekked some 270 miles until he found the source of his discovery.
Alibert had supplies packed in by reindeer to set up a mine at this mountainous site near the Chinese border. During the first seven years of operation, the mine produced graphite of marginal quality. Then a rich and unbroken deposit of the highest-quality graphite was uncovered, a find that yielded pieces of pure ore weighing as much as 80 pounds! Pencils using Asian graphite were painted yellow as an indication of the source of the superior material in the writing core.
Pencil Leads Today.
Today's graphite writing cores are a mixture of graphite and clay. By varying the ratio of graphite to clay, pencil makers can adjust the "hardness" of the writing core. The hardness of the graphite core is usually marked on the pencil with a number such as 2, 2-1/2 or 3 or letters such as HB,2B, H or F. Learn more about the HB Scale for grading graphite leads.
Another popular form of blacklead pencil used by artists is the charcoal pencil which is made from a different form of carbon than graphite more like coal. These make a very dark black mark on the paper compared to even very soft graphite pencils such as 8B.
Beyond graphite pencils there are other types of pencil leads used for many different purposes that make different.
Color Leads.
Color pencils leads that mark with different colors are made through a similar process of creating a blend of pigment, china clay and wax that is extruded into a lead. Some basic sets of color pencils come with 12 or 24 colors per carton, but other high quality sets for art purposes include up to 120 different colors or more.
Some color leads have the added feature of being washable in water so that they can be used similar to watercolor paints. These pencils are called aquarelle or water colori pencils.
Some special color leads are also used for make-up purposes in cosmetic pencilsi to be used as eye or lip liner.
And some color pencils called pastel pencils make a mark similar to chalk and look especially good on dark papers.
This video produced by Cumberland Pencil Comany demonstrates the process to make both graphite and color leads for use in pencils.