A Staff Report from the Straight Dope Science Advisory Board

How come you see #2 pencils but no #1 pencils?

July 1, 2003

Dear Straight Dope:

What exactly is a #2 pencil and why isn't there a #1 pencil?

Of course there's such a thing as a #1 pencil. What else would the mathematician use to work out his calculus problem?

All joking aside--did you miss the joking?--there are #1 pencils, and #2.5, #3, and #4 and sometimes other intermediate grades, and you can buy them all at finer stationery stores everywhere (and now online too). Some people believe that the #2 pencil is so called because it used to be the second most common, but that's not the case. For as long as pencils have been available in different grades, the #2 or its equivalent has been the most popular for general use. It's called #2 because it's the second darkest of the four major grades of pencil marketed under this system. There's a trade-off between hardness and darkness (in pencil leads I mean), and the #2 is the best compromise for most purposes.

The #1 pencil has the softest and darkest lead, but most people find that it smudges too easily and needs resharpening too often to make it appropriate for everyday writing. It is sometimes recommended for writing on the backs of photographs because it leaves a readable mark without requiring as much potentially damaging pressure as harder leads. The #2.5 pencil is harder than the #2, but it's not as popular because it leaves a lighter mark that some people find hard to read. It is often recommended for taking stenographic notes because it requires less frequent sharpening. The #3 and #4 pencils are harder and lighter yet, and even less popular for everyday writing.

But that's only one grading system, and it's not very common outside the U.S. Even in America, it's used mostly for inexpensive general-purpose writing pencils, which are typically sold by the dozen and have attached erasers. A different system is more popular in other parts of the world and is also used in the U.S. for high-quality drafting and drawing pencils, which are usually sold individually or in sets of assorted grades, usually without erasers attached. This latter system encompasses a much wider variety of hardnesses, from 9B (much softer and darker than #1) to 10H (much harder and lighter than #4).

In this system, B stands for "black" and H for "hard," blackness and hardness representing the opposite ends of the grading scale. (One might have thought it'd be less confusing to use a pairing like hardness and softness, but we weren't consulted.) The numbers indicate degree of hardness or blackness, so 8H is harder than 7H, for example. The black end of the scale is popular for sketching, the hard end for drafting. In the middle of the scale are the grades corresponding to the number grades for inexpensive writing pencils: B = #1, HB = #2, F = #2.5, H = #3 and 2H = #4. HB stands for "hard" and "black" because it is a good compromise between the two qualities. (Now you know why many #2 pencils are also marked HB.) The anomalous F grade is of questionable origin and may stand for "fine," "fine point," or "firm," depending on which source you believe. Over the years, other grading systems have also been used. One ranged from HH (extra hard) to SS (extra soft) and a variation ran from VVVH (very very very hard) to VVVS (very very very stupid--er, soft).

All these grading systems were made possible by the modern manufacturing process that allows reproducible variation in lead hardness. At first all graphite pencil leads were made from native graphite (graphite as it comes out of the ground), cut into long thin pieces. For a long time, the only graphite of quality high enough to be used this way came from the Lake District of England. These pencils weren't cheap, so sometimes substitutes were made with low-quality graphite from other regions, ground into a powder, mixed with a binder such as molten sulfur or glue, and allowed to harden. But the results were less than satisfactory.

In 1795, when good pencils weren't available in France because of the English blockade, a French scientist named Nicholas-Jacques Conté invented a new process to make good quality pencil leads from poor quality graphite. Conté's process is still used today for making almost all pencil leads, with only minor changes since his time. First the graphite is ground to a fine dust, washed in water, and thoroughly mixed with high quality washed clay and water. The mixture is then shaped, dried and fired in a kiln at around 1000° C. The entire process can take several weeks, but the resulting ceramic lead is far superior to the earlier sulfur-and-graphite lead. The best ceramic leads are generally held to approach the quality of the best native graphite leads, but at much lower cost. Good thing--since the best mines (Borrowdale in the Lake District and the Alibert mine in Siberia) have been worked out, top quality native graphite is pretty much unavailable.

The wide range of standardized pencil grades is a side benefit of Conté's process. There is some variation in native graphite leads, depending on impurities, but getting a lead with just the right hardness for your purposes was a hit-or-miss proposition. Conté discovered that in his process a high clay content reliably produced a hard, light lead and a low clay content reliably produced a soft, dark lead. Recognizing the need for different hardnesses for different applications, Conté produced pencils in four numbered grades, but his system was the reverse of the modern American system--his #1 was the hardest, while our #1 is the darkest.

One more thing. If your grade school was anything like mine, there was always some geeky kid ready to taunt you for calling it a pencil lead. "It's not made from lead, it's made from graphite," I would--er, I mean he would say. But in a world of electronic newspapers, cotton table linens, titanium golf woods, resin eyeglasses and plastic wine corks, I think we can make room for graphite pencil leads. The others are named for the substance they are traditionally made of, and pencil leads aren't much different. Lead and alloys of lead with tin, bismuth, antimony or other metals were used for writing in earlier eras, and graphite can be seen as a modern substitute, though much superior to the original. Indeed, for many years after graphite was discovered in the Lake District in the sixteenth century, it was widely thought to be a variety of lead. By the end of the seventeenth century, scientists knew it was non-metallic, but it wasn't until 1779 that Swedish chemist K. W. Scheele proved it was a form of carbon.

So if you get stabbed with a lead pencil, you're not going to get lead poisoning, despite what my fourth grade teacher said. But if you do get stabbed and if any of the graphite gets lodged in the dermis of your skin, it's likely to stay there for life. The result is a pretty much harmless accidental tattoo, as one of my fourth grade classmates learned the hard way. (I still say he deserved it for calling me "some geeky kid.") And although I haven't tried it on anybody yet, I always believed my mother when she told me you could put an eye out with that thing. Of course, if you've got an eraser on the end of it, you can put an i out too.

Further reading:

The Pencil: A History of Design and Circumstance by Henry Petroski (1989)

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