Curtis and Cory Jenkins, 9 year old twins from Centerville, Utah, for their question:
HOW ARE PENCILS MADE?
We usually call them lead pencils, but they do not contain lead. The so called lead is made up of crystals of carbon in a form called graphite. "Graphite" comes from the Greek word for "writing." The crystals are of such a shape that they can easily be rubbed away from one another as we write.
A pencil, of course, is a thin tube of graphite encased in wood or other material and used for writing or drawing. We know they have been in use since the mid 1500's.
The first pencil factory was built in 1761 by Casper Farber in Nuremberg, Germany, with the first American production started in Concord, Mass., in 1812 by William Monroe.
The most practical method of combining graphite and a special type of clay in making pencil lead was developed by N.J. Conte of Paris in 1795. The same method, only slightly modified, is still used today.
Graphite, a 99.9 percent fine carbon, is received at a pencil factory in powder form. It is then mixed with clay and water to form a smooth, thick paste. The proportion of clay used in the formula determines the hardness of the finished pencil. A pencil of medium grade is made up of seven parts of clay to 10 parts of graphite.
Next the mixture is placed in canvas bags and under hydraulic pressure to remove the water. The thick mass is then passed through forming presses which squeeze the graphite mixture into thin coils. These are then straightened, cut into sticks and baked in kilns.
Cedarwood is used for most pencils. This wood used to come from a number of Southern states but supplies were depleted. Western incense cedar is mainly used now and obtained from trees in California.
Wood for the pencils is cut into grooved strips, each long enough and half as thick as six pencils. The strips are separated into pairs, coated with glue on the grooved sides, pencil lead placed in the grooves and then the two halves are put together. After they're completely dry, the strips are trimmed twice and then passed through a lacquer bath from three to 12 times, depending on the quality of the finish desired.
Most pencils have ferrules and erasers at one end. The caps are usually made of brass although plastic is also used. The erasers are made of rubber, filler and a fine abrasive.
Pencils are put into five grades: 1, very soft; 2, soft; 2 2 3, medium; 3, hard; 4, very hard. Drawing pencils are made in 17 grades.