Pencil

A pencil is a writing instrument 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.

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, a form of early paper. The word pencil comes from the Latin word pencillus which means "little tail."

Discovery of graphite deposit
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"). 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.

Wood holders added
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&mdash;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 neighbouring 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.

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 (thermally insulated chambers). 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.

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. According to Petrosky this system might have been developed in the early 1900s by Brookman (an English pencil maker) which used "B" for black and "H" for hard; a pencil's grade was described by a sequence or successive Hs or Bs such as BB and BBB for successively softer leads, and HH and HHH for successively harder ones. .

Today a set of pencils ranging from a very hard, light-marking pencil to a very soft, black-marking pencil usually ranges from hardest to softest as follows.



Koh-i-noor offers twenty grades from 10H to 8B for its 1500 series ; Derwent produces twenty grades from 9B to 9H for its Graphic pencils and Staedtler produces sixteen from 8B to 6H for its Mars Lumograph pencils. The main market for such wide range of grades are artists who are interested in creating a full range of tones from light grey to black; while engineers prefer harder pencils which allow for a greater control in the shape of the lead. This is reflected in the way pencils are packaged and marketed. For example, for its Graphic pencils Derwent offers three packages of 12 pencils each: Technical (with hard grades from B to 9H), Sketching (with soft grades 9B to H), and Designer (with medium grades 6B to 4H).

Pencils graded using this system are used to measure the hardness and resistance of varnishes and paints. The resistance of a coating (also known as its pencil hardness) is determined as the grade of the hardest pencil that does not mark the coating when pressed firmly against it at a 45 degree angle.

Another common method uses numbers to designated the grade of a pencil. It was originally created by Conté and adopted in the United States by Thoreau in the 19th century. The following table shows approximate equivalences between the different systems :

* Also seen as 2-4/8, 2.5, 2-5/10. Although widely accepted, not all manufacturers follow it; for example, Faber-Castell uses a different equivalence table in its Grip 2001 pencils: 1=2B, 2=B, 2 1/2=HB, 3=H, 4=2H.

The various graphite pencil grades are achieved by altering the proportion of graphite to clay: the more clay the harder the pencil. Two pencils of the same grade but different manufactures will not necessarily make a mark of identical tone nor have the same hardness.

Colour of pencils
The majority of pencils made in the United States are painted yellow. According to Henry Petroski, this tradition 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 (renamed Mirado ) and Mongol.

Not all countries use yellow pencils, however; German pencils, for example, are often green, based on the trademark colours of Faber-Castell, a major German stationery company. Pencils are commonly round, hexagonal or sometimes triangular in section.

According to the material used to make them

 * Graphite pencils
 * Charcoal pencils
 * Crayon pencils
 * Grease pencils. They write on virtually any surface (including glass, metal and photographs).
 * Watercolour pencils

According to their use



 * Carpenter's pencils. These are pencils that have two main properties: their shape prevents them from rolling, and their lead is strong . The oldest surviving pencil is a German carpenter's pencil dating from the 17th Century and now in the Faber-Castell collection.
 * Copying pencils are graphite pencils with an added dye that creates an indelible mark. They were invented in the late 1800s for press copying and as a practical substitute to fountain pens. Their markings  are often visually indistinguishable from those of standard graphite pencils, but when moistened their markings dissolve into a coloured ink, which is then pressed into another piece of paper.   There were used until the early 1900s when ball pens slowly replaced them.
 * Col-erase. There are colour pencils that can be easily erased. Their main use is in sketching, where the objective is to create an outline using the same colour that other media (such as wax pencils, or watercolour paints) would fill or when the objective is to scan the colour sketch . Some animators prefer col-erase to graphite pencils because they don't smudge as easily, and the different colours allow for better separation of objects in the sketch . Copy-editors find them useful too, as their markings stand out more than graphite but can be erased . Col-erase is a trademark owned by Sanford (owner of Prismacolor and Berol) and for this reason other companies use the "erasable colour pencil" moniker (e.g. Dixon Erasable Coloured Pencils ).
 * Non-reproducing pencils make marks that are not reproduced by photocopiers (Sanford's Copy-not or Staedtler's Mars Non-photo) or by whiteprint copiers (Stedtlers Mars Non print). They are commonly known as copy-not.
 * Stenographer's pencil, also known as steno pencil. These pencils are expected to be very reliable, and their lead is break proof. Sometimes steno pencils are sharpened at both ends.
 * Golf pencil

According to their shape

 * Triangular
 * Hexagonal
 * Round

Other types

 * 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.
 * Penny pencil

Graphite is not poisonous
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. 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.

First pencil with an attached eraser


On March 30, 1858, Hymen Lipman received the first patent for attaching an eraser to the end of a pencil. In 1862 Lipman sold his patent to Joseph Reckendorfer for $100,000, who went to sue Faber for infringement. In 1875 the Supreme Court of the United States ruled against Reckendorfer declaring the patent invalid.

Mechanical pencils
There are also mechanical pencils, which use mechanical methods to push lead through a hole at the end. The erasers are also removable (and thus replaceable), and usually cover a place to store replacement leads. Mechanical pencils are popular 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.