|
History The archetypal pencil may have been the ancient Roman stylus, which was a thin metal stick, often made of lead and used for scratching on papyrus. The word pencil comes from the Latin word penicillus which means "little tail". Some time prior to 1565 (some sources say as early as 1500), an enormous deposit of graphite was discovered at the site of Seathwaite Fell near Borrowdale, Cumbria, England. The locals found that it was very useful for marking sheep. This particular deposit of graphite was extremely pure and solid and it could easily be sawn into sticks. This was and remains the only deposit of graphite ever found in this solid form. Chemistry was in its infancy and the substance was thought to be a form of lead. Consequently it was called plumbago (Latin for "acts like lead"). The black core of pencils is still sometimes referred to as "lead", even though it never contained the element lead. The value of plumbago was soon realised to be enormous, mainly because it could be used to line the moulds for cannon balls, and the mines were taken over by the Crown and guarded. Graphite had to be smuggled out for use in pencils. Because the plumbago was soft, it required some form of case. Plumbago sticks were at first wrapped in string or in sheepskin for stability. The news of the usefulness of these early pencils spread far and wide, attracting the attentions of artists all over the "known world". Although deposits of graphite had been found in other parts of the world, they were not of the same purity and quality as the Borrowdale find, and had to be crushed to remove the impurities, leaving only graphite powder. England continued to enjoy a monopoly on the production of pencils until a method of reconstituting the graphite powder was found. The distinctively square English pencils continued to be made with sticks cut from natural graphite into the 1860s. Today, the town of Keswick, near the original findings of block graphite, has a pencil museum. The first attempt to manufacture graphite sticks from powdered graphite was in Nuremberg, Germany in 1662. They used a mixture of graphite, sulphur and antimony. Though usable they were inferior to the English pencils. It was the Italians who first thought of wooden holders. An Italian couple in particular named Simonio and Lyndiana Bernacotti were believed to be the ones to create the first blueprints for the modern carpentry pencil for the cause of being able to mark their carpentry pieces, however, their version was instead a flat oval, more compact type of pencil. They did this at first by hollowing out a stick of juniper wood. Shortly thereafter, a superior technique was discovered: two wooden halves were carved, a plumbago stick inserted, and the two halves then glued together—essentially the same method that is in use to this day. English and German pencils were not available to the French during the Napoleonic wars. It took the efforts of an officer in Napoleon's army to change this. In 1795 Nicholas Jacques Conté discovered a method of mixing powdered graphite with clay and forming the mixture into rods which were then fired in a kiln. By varying the ratio of graphite to clay, the hardness of the graphite rod could also be varied (the more clay, the harder the pencil, and the lighter the colour of the mark). This method of manufacture remains in use today. American colonists imported pencils from Europe until after the American Revolution. Benjamin Franklin advertised pencils for sale in his Pennsylvania Gazette in 1729, and George Washington used a three-inch pencil when he surveyed the Ohio Territory in 1762. It is said that William Munroe, a cabinetmaker in Concord, Massachusetts, made the first American wood pencils in 1812. This was not the only pencil-making in Concord. According to Henry Petroski, transcendentalist philosopher Henry David Thoreau discovered how to make a good pencil out of inferior graphite using clay as the binder; this invention was prompted by his father's pencil factory in Concord, which employed graphite found in New Hampshire in 1821 by Charles Dunbar. William Munroe's method of making pencils were painstakinly slow, and in the neighboring town of Acton, Massachusetts a pencil owner by the name of Ebenezer Wood set out of automate the process at his own pencil mill located Nashoba Brook along the old Davis Road. He used the first circular saw in pencil production. He constructed the first hexagon and octagon shaped pencil cases that we have today. Ebenezer did not patent his invention and shared his techniques with those who asked. One of those was Eberhardt Faber of New York, whose became the leader in pencil production. Many great artists have used pencils to sketch their painting/drawing before they do the real thing. Manufacture Modern pencils are made industrially by mixing finely ground graphite and clay powders, adding water, forming long spaghetti-like strings, and firing them in a kiln. The resulting strings are dipped in oil or molten wax which seeps into the tiny holes of the material, resulting in smoother writing. A juniper or incense-cedar plank with several long parallel grooves is cut to make something called a slat, and the graphite/clay strings are inserted into the grooves. Another grooved plank is glued on top, and the whole thing is then cut into individual pencils, which are then varnished or painted. Many pencils, particularly those used by artists, are labelled on the European system using a "degrees" scale from "H" (for hardness) to "B" (for blackness), as well as "F" (for fine point). The standard writing pencil is "HB". However, artists' pencils can vary widely in order to provide a range of marks for different visual effects on the page. A set of art pencils ranging from a very hard, light-marking pencil to a very soft, black-marking pencil usually ranges from hardest to softest as follows: The American system, using numbers only, developed simultaneously with the following approximate equivalents to the European system. It was developed by Nicolas-Jacques Conté *. Even though the natural deposits of pure graphite are tapped out, it is still possible to write the way Englishmen did centuries ago, without clay or wax additives leaving oily stains on paper. Chemical supply companies commonly sell 99.995% pure graphite rods in 3 mm and 6 mm diameters. Colour of pencils
Pencils in space An urban legend in circulation since the 1970s (and told on a 2002 episode of The West Wing) tells of NASA spending large sums of money, typically in the millions of dollars, to develop an instrument that would write in space (a space pen). This task is not as simple as it seems, as standard ballpoint and fountain pens require gravity in order to function. The typical punch line is that either someone supposedly should have sent NASA a pencil, or that the Soviets used pencils. While considered humorous, the story is not true (see Snopes for details). In fact, lead pencils were used on all Mercury and Gemini space flights, and were replaced by pressurized "space pens" (independently developed without NASA funding) only after the Apollo 1 fire. Pencils are, in fact, still used in space, for example aboard the International Space Station. Miscellaneous The pencil is a common cause of minor puncture injuries in young children. The tip of the lead may leave a grey mark inside the skin for years. This led to the old wives' tale that the lead bits could be passed through the blood vessels into the brain, causing mental retardation in those with such a wound. Of course, pencil "lead" is graphite (carbon), and not the element lead, so it is not poisonous, and is harmless if consumed. On March 30, 1858, Hymen Lipman of Philadelphia, Pennsylvania, USA, received the first patent for attaching an eraser to the end of a pencil. It was later invalidated because it was determined to be simply a composite of two devices rather than an entirely new product. There are also mechanical pencils, which use mechanical methods to push lead through a hole at the end. The erasers are also enabled to come off so the user can insert new lead. Lead types are based on thickness. Common sizes are 0.3, 0.5, 0.7, 0.9, 1.1, and 1.6 millimetres. The 2.0 mm size is commonly used in designing, artwork and engineering, but is not commonly used outside these fields due to its high cost. Mechanical pencils are popular in schools for their longevity and the fact that you never have to sharpen them. See also | ||||||||||||
|
| |||||||||||||
 |
|
| |