It is inexpensive, instantly ready, and almost weightless. It sits comfortably in the pocket. It needs no power supply, it never leaks, and its marks can be erased. Children learn to write with it, accomplished artists create masterpieces with it , and most of us keep one handy for jotting down notes. Yes, the humble pencil is one of the most affordable and widely used writing instruments in the world. The amazing story of its invention and development begins with a chance discovery in rural England.
In the 16th century, lumps of a strange black substance were found beneath the hillside of Borrowdale, a valley in the Lake District of northern England. Although the mineral looked like coal, it did not burn; and it left a shiny, black easily erased mark on a writing surface. Initially, the substance had a variety of names - black lead, wad, and plumbago, meaning "that which acts like lead". Because it had a greasy texture, people wrapped chunks of it with sheepskin or short sticks of with string. No one knows who first thought of putting black lead into wooden holders, but by the 1560's, primitive pencils had reached the European continent.
Soon black lead was being mined and exported to meet the demands of artists; and in the 17th century, it was being used practically everywhere. At the same time, pencil makers experimented with black lead to produce a better writing instrument. Pure and easily extracted, the Borrowdale product became a target of thieves and black marketers. In response, the British Parliament passed a law in 1752 making the theft of the material punishable by imprisonment or banishment to a penal colony.
In 1779, Swedish chemist Carl W Scheele made the surprising discovery that black lead was not lead at all but a soft form of pure carbon. Ten years later German geologist Abraham G Werner named it graphite, from the Greek graphein, "to write". Yes, contrary to their name, lead pencils actually contain no lead at all!
For many years English graphite cornered the pencil-making industry because it was pure enough to use without further processing. Since European graphite was inferior, pencil manufacturers there experimented with ways to improve pencil leads. French engineer Nicolas-Jacques Conté mixed powdered graphite and clay, shaped the mixture into sticks, and fired them in a kiln. by varying the ratio of graphite to clay, he was able to make leads that produced different shades of black - a process still in use. Conté patented his discovery in 1975.
In the 19th century, pencil making became big business. Graphite was discovered in a number of places, including Siberia, Germany and what is now the Czech Republic. In Germany and then the United States, a number of factories opened up. Mechanisation and mass production drove prices down, and by the start of the 20th century, even school children were using pencils - unpainted "penny pencils" as they were called in the US.
With many billions manufactured world-wide each year, the pencil has become a sophisticated, versatile writing and drawing instrument. A typical wooden pencil can draw a line 56 kilometres long and write 45,000 words. Made of metal or plastic, mechanical (or, propelling) pencils hold thin leads that never need sharpening. In the place of graphite, coloured pencils use dyes and pigments that come in dozens of colours.
Versatile, robust, simple, and efficient, the lowly pencil shows no signs of obsolescence. Hence, for years to come, whether at home or at work, you may still hear someone ask, "Does anyone have a pencil?"
How does the lead get into the pencil? A solution of finely ground graphite, clay and water is forced through a narrow metal tube and comes out looking like a long string of spaghetti. After being dried, cut and fired in a kiln, the lead is immersed in hot oil and wax. The wood, usually cedar, which is easily sharpened, is sawed into slats - planed and grooved pieces of wood - half a pencil thick. The leads are inserted into the grooves on one slat, and a second slat is glued and pressed on top of the first. When the glue dries, the individual pencils are cut apart. After shaping, sand-papering, painting and stamping with the manufacturer's trademark and other details, the now seamless pencil is ready for use. Sometimes an eraser is attached to one end.
Which pencil should I use? To select the pencil you need, note the letters or numbers printed on the side of the pencil. These indicate the degree of hardness or softness. Softer leads leave a darker mark.
HB is a versatile, medium-grade lead.
B denotes softer leads. A number such as 2B or 6B denotes the degree of softness - the higher the number, the softer the lead.
H denotes harder leads. The higher the number 2H, 4H, 6H, and so on - the harder the lead.
F stands for fine point.