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Geologic Column
Pick Up Your Pencils, Please
Lisa A. Rossbacher

We all know that a “lead pencil” doesn’t really have lead in it, but once upon a time, writing instruments were made of lead. The Greeks and Romans used small lead disks to mark papyrus before writing with a brush and ink. In the 14th century, “silverpoint” involved drawing with rods of lead, zinc or silver; this technique is still used by artists today. Around 1560, lead was replaced with a much better material: graphite.

Konrad Gesner, a paleontologist from Zurich, wrote the first description of a writing instrument encased in wood. He mentioned his pencil as an aside in his 1565 treatise on fossils. Indeed, Gesner has been credited — probably wrongly — with the invention of the pencil.

The true origin of the pencil was in 1564, when a large deposit of graphite was discovered, and the sticks cut out of the material were called black lead or “plumbago,” from the Greek word for lead. It looked like lead and made marks like lead, although it certainly did not have the heft of lead. This deposit of graphite in Borrowdale in northern England was the purest one ever discovered — and one of the most valuable. The deposit was mined only six weeks a year, and armed guards escorted the excavated graphite to London, where the English Guild of Pencilmakers had a global monopoly on its product.

Other groups began investing considerable energy into finding alternate ways to make pencils, to escape the dependence on this single source of graphite. German manufacturers, for example, used a variety of materials, including resins, glue and sulfur, to cement powdered graphite into sticks. They had some success, but it was nothing compared to the English original.

The first chemical analysis of the “pencil lead” was made in 1779, when K.W. Scheele discovered that “plumbago” was actually carbon. In 1789, A.G. Werner suggested the name “graphite,” from the Greek “to write.”

But it was the Napoleonic Wars that contributed most to the pencils we use today. The war caused a major shortage of high-quality graphite, as well as major trade issues for France that made both English and German sources of pencils unavailable. A French chemist, who was also an officer in Napoleon’s army, invented the recipe for modern pencil “leads.” Nicholas Conté mixed powdered graphite and clay in varying proportions and fired it in a kiln-like porcelain.

So here’s a challenge. How do you grind graphite, whose crystalline structure also makes it a terrific lubricant? You “fight fire with fire” and use compressed air to fire the graphite particles at each other. When the particles collide at high speed, they fracture. The particles are mixed with clay and water to make a paste, formed into a cylinder, dried in an oven and then fired at 1200 degrees Celsius.

Not only did Conté create a way to make usable “leads,” but also his manufacturing process offered enough control over the end product that the sticks could be “graded” from hard to soft.

The proportion of clay is the most important factor in the hardness or softness of lead, although temperature is a secondary contributor. The more clay that is mixed in, the harder the lead will be. Conté described the hardness of his products on a numerical scale: 1 was the hardest, and 4 was the softest. In the 19th century, English pencil makers started using letters to identify hardness; harder leads were designated with H and softer leads with B (for black, as opposed to the more intuitive S, for soft). Thus, BBB is softer than BB, and HHH is harder than HH.

By the early 20th century, most European- and many American-made pencils were graded by a combination of letters and numbers, with the series 9H, 8H, ... , 2H, H, F, HB, F, B, 2B, … , 8B, 9B. Today, in the United States, a number-only system describes hardness. A no. 1 pencil is graded B, no. 2 is HB, no. 2 1/2 is F, no. 3 is H, and no. 4 is 2H. Draftsmen prefer harder leads; artists prefer softer ones.

The pencil has come to be a symbol of anti-technology. The “Lead Pencil Club” was established in 1993, and its purpose depends on your point of view. Either the members’ refusal to use electronic communication tools is a rejection of technology or it is a celebration of the simplest tool of written communication. The founder, Bill Henderson, published a book titled Minutes of the Lead Pencil Club: Pulling the Plug on the Electronic Revolution (1995, Norton), which offers cautionary advice about the dangers of information overload.

Perhaps one of the most enduring modern connections to the pencil is the SAT:

“Now turn to page 1 of your answer sheet. Make sure you are using a no. 2 pencil to mark your answer sheet in the spaces provided. Otherwise your answers, which are scored electronically, will not register correctly” (SAT Program Supervisor’s Manual, October 2004-January 2005).

There is nothing simpler, more basic or more useful than a no. 2 pencil. We owe a debt of gratitude to the geology of Cumbria, England, the Napoleonic Wars and Nicholas Conté. Most students, on hearing the call to action at the beginning of the SAT, won’t have gratitude on their minds. But you never know when there will be a question about graphite.

Rossbacher, a geologist, is president of the Southern Polytechnic State University in Marietta, Ga.

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