Pencil

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This article is about the handwriting instrument. For other uses, see Pencil (disambiguation).

A pencil is a writing or drawing instrument consisting of a thin stick of pigment (usually graphite, but can also be coloured pigment or charcoal) and clay, usually encased in a thin wood cylinder though paper and plastic sheaths are also used. Pencils are distinct from pens, which use a liquid marking material.

[edit] 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 pencillus 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 "lead ore")^[1][2]. The black core of pencils is still sometimes referred to as "lead," even though it never contained the element lead.

The value of graphite was soon realized 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 graphite is soft, it requires some form of case. Graphite 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. It 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 purpose of marking 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 graphite stick inserted, and the two halves then glued together—essentially the same method 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 that were then fired in a kiln. By varying the ratio of graphite to clay, the hardness of the graphite rod could also be varied. This method of manufacture which had been earlier discovered by the Austrian Joseph Hardtmuth of Koh-I-Noor in 1790 remains in present use.

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.

Munroe's method of making pencils was painstakingly slow, and in the neighboring town of Acton, a pencil mill owner named Ebenezer Wood set out to automate the process at his own pencil mill located at 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 whoever asked. One of those was Eberhard Faber of New York, who became the leader in pencil production.

Joseph Dixon, an inventor and entrepreneur involved with the Tantiusques granite mine in Sturbridge, Massachusetts, developed a means to mass produce pencils. By 1870, The Joseph Dixon Crucible Company was the world’s largest dealer and consumer of graphite and later became the contemporary Dixon Ticonderoga pencil and art supplies company.^[3][4]

[edit] 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.

[edit] Grading & classification

Many pencils across the world and almost all in Europe are graded on the European system using a continuüm from "H" (for hardness) to "B" (for blackness), as well as "F" (for fine point). The standard writing pencil is graded HB. However, artists' pencils can vary widely in order to provide a range of marks for different visual effects on the page. Pencils graded with different schemes were used to expand the range of grades, such as BB and BBB for successively softer leads, and HH and HHH for successively harder leads between the early 19th century and beginning of the 20th century. Today 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.

* Also seen as 2-4/8, 2.5, 2-5/10, due to patent issues

The various pencil grades are achieved by altering the blend of graphite, clay, and wax:^{[citation needed]}

Even though the known 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.

Various coatings are rated using the pencil hardness test. These coatings are used for paint, plastics and coatings for furniture. Below is a list of ratings for a variety of coatings. Type of coatings: Pencil Hardness Catalyzed polyester: 9H Catalyzed polyurethane: 9H Catalyzed Modified Acrylic polyurethane: 4H Catalyzed Acrylic polyurethane: 2H Water-based polyurethane: 3H Low VOC Catalyzed lacquer [24 hrs]: 2H Low VOC lacquer: 3H Urethane/Nitrocellulose lacquer [24 hrs}: F

[edit] Color of pencils

Pencils in the United States and Canada tend to be painted yellow on the outside. According to Henry Petroski, this tradition now extends to a majority of pencils worldwide and began in 1890 when the L. & C. Hardtmuth Company of Austria-Hungary introduced their Koh-I-Noor brand, named after the famous diamond. It was intended to be the world's best and most expensive pencil, and at a time when most pencils were either painted in dark colours or not at all, the Koh-I-Noor was yellow. As well as simply being distinctive, the colour may have been inspired by the Austro-Hungarian flag; it was also suggestive of the Orient, at a time when the best-quality graphite came from Siberia. Other companies then copied the yellow colour so that their pencils would be associated with this high-quality brand, and chose brand names with explicit Oriental references, such as Mikado and Mongol.

Not all countries however use yellow pencils; German pencils, for example, are often green, based on the trademark colours of Faber-Castell, a major German stationery company. Brazilian low-cost pencils are usually black with a round section, but may sometimes be brown, light green, metallic light blue, yellow or orange; while most pencils are round, hexagonal pencils are quite common too, and there is a growing market of triangular pencils. The traditional low-cost pencil in Argentina is black (no specific tradename), but the typical expensive, high-quality pencil is black and red or black and yellow (Faber-Castell). Low-cost pencils made by German company Staedtler are yellow (available in 3 hardnesses), while the higher end pencils are red and black (12 hardnesses) and the highest end pencils blue (16 hardnesses). In Australia most pencils are painted bright red, though other colours are becoming more common.

[edit] 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). 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.^[5] In fact, graphite pencils were used on all Mercury and Gemini space flights, and were replaced by pressurized "space pens" (independently developed without NASA funding) after the Apollo 1 fire. Pencils are, in fact, still used in space, for example aboard the International Space Station.

[edit] Quadrachromic Pencil

The Quadrachromic Pencil is a slightly enlarged pencil with four colours equally partitioned on the tip. The use of each colour while drawing is accomplished by rotating the pencil between the fingers.

[edit] Miscellaneous

Pencils are students' primary writing instruments. Due to this common usage, 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. But of course, pencil "lead" is graphite (carbon) and not the chemical element lead. Residual graphite from a pencil stick does not seem to be poisonous, and graphite is generally harmless if consumed.

On March 30, 1858, Hymen Lipman of Philadelphia, Pennsylvania, U.S., 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 removable so that the user can insert new lead. Mechanical pencils are popular in schools for their longevity and the fact that they never need sharpening.

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. This largest size usually cannot be sharpened in pencil sharpeners: a variety of devices are used, mostly abrasive.