Pencils are implements designed to make marks on paper. They come in a massive range of different types: the most basic kind is a stick of graphite and clay surrounded by a wood casing to prevent the fingers becoming dirty. This wood casing is a development of early pencil designs, which began with a lump of graphite used to draw on a cave wall, then progressed gradually, being shaped and perhaps wrapped in plant fibre or leather, before the method of packing the lead in wood was developed. The cases can come with different shaped cross sections, normally hexagonal, but often circular, and sometimes even triangular.

The Lead

Pencil 'leads' are actually not made of lead. Modern leads are in fact a mixture of graphite (a soft allotrope¹ of carbon) mixed with clay and baked in an oven. The grade of the lead can be altered to change the density of the marks made upon the paper. The grade is altered by using different proportions of graphite and clay; more graphite, and the lead becomes softer, producing thicker, blacker marks which smudge; more clay, and the lead becomes harder, producing thinner, lighter marks more suited to technical drawing. In the United Kingdom, there is a grading system for the hardness of pencil leads, which is described as follows:

HB is a medium grade lead suitable for most tasks involving writing or scribbling. However, it is not particularly good for sketching or technical drawing. Softer leads are denoted using the letter B and a number, for instance 2B, which is fairly soft, black and good for sketching; although softer pencils are also used by artists. Typically, pencils up to 6B or 9B can be obtained. H denotes harder pencils. 2H is quite a hard lead and holds a good point so is excellent for accurate drawing - although not as good as a 4H or 6H. The harder a pencil is, the lighter the mark it makes on paper, so very hard pencils are very impractical due to their near invisibility. Thus 9H pencils are something of a rarity.

Other countries use different systems for categorizing their pencils. For instance, in America, a #2 pencil is equivalent to an HB, while a #1 is softer and a #3 or #4 is harder.

Sharpening

The standard pencil requires sharpening from time to time as the lead wears away. This process involves removing some of the wooden casing to expose more lead, and then shaping the lead into a point for better writing or drawing. The usual way to accomplish this involves the use of a pencil sharpener, which is often a plastic or metal device with a blade set in it, such that when the pencil is inserted and turned, a thin layer is sliced from the outside. More sophisticated pencil sharpeners include built-in bins for catching the shavings and some are desk-mounted with a handle to turn. Electric pencil sharpeners, which activate when a pencil is placed in the hole, are a good way to waste large amounts of pencil by sharpening it all away.

Not all people like to use pencil sharpeners. Artists are often known to use a sharp knife to sharpen their pencils as they can get a longer piece of exposed lead which is more suitable for drawing with. Draughtsmen sometimes use a sanding block to shape their lead into a chisel shape, allowing them to vary the thickness of the line by turning the pencil slightly in the hand. Some people have been known to sand the leads of propelling pencils to make them sharper, although this can generally be seen as overkill, or only for those people who need a really, really fine line.

The Propelling Pencil

A more modern version of the pencil is the 'propelling pencil' or 'mechanical pencil'. This device looks more like a biro (ballpoint pen) than anything else, but it is still a type of pencil. Within their tips is a mechanism which holds thin leads, anything from 0.2 to 0.7mm in diameter, in a variety of grades. As the lead is worn down, a button², usually on the end of the pencil, can be pressed to feed more lead out. This button makes a satisfying clicking sound, causing bored students in lectures and lessons to click their pencils endlessly. Propelling pencils normally have several spare leads inside the body, providing a much greater writing time, and it is possible to buy refill packs which are really quite astoundingly cheap. The great advantage of the propelling pencil is that it does not need sharpening. However, due to the thinness of the leads (typically 0.5mm), they are not generally available any softer than HB. Although 2H leads are typically available, they are not always easy to find, which is a shame, because the constant thickness of the propelling pencil makes it superb for technical work.

Another advantage of propelling pencils is that they frequently have a small eraser under the cap at the end, which has the additional purpose of stopping all the spare leads inside the pencil from falling out. This eraser is not normally very useful, however, as it is frequently all used up well before the pencil's initial complement of leads. It is also often of fairly low quality, so a separate eraser is frequently a far better option.

Alternative Uses of the Pencil

Like many objects, pencils can also be used for things other than that which they were originally intended for. Such alternative uses for pencils include:

• Spinning around your fingers when you're bored - if you have the patience to learn how.

• Sticking up your nose in order to enhance the effect of putting your thumbs in your ears and waggling your fingers at someone.

• Adjusting the tiny DIP switches found on some computer equipment, especially older printers and motherboards.

• A major component for a rubber band launcher.

• A tool for releasing aggression; when snapped in half, wooden pencils can relieve a great deal of stress.

• Expressing anger - snapping a pencil is a good way to show your friends and work mates that you are becoming angry... an office version of baring fangs.

• Gnawing - a common habit, this is not so pleasant with painted pencils as the paint tends to flake off in the mouth, requiring a trip to the toilet and lots of spitting.

• Staring at - many organizations produce promotional pencils with designs on. Staring at an American Dental Association pencil, which features lines of teeth marching along, after a Pink Floyd concert is said to be particularly hypnotic.