Differences between #2 lead and other types of pencil lead.
Pencils have been around for longer than you may think! It all started in 16th century England when several trees, downed by a furious storm, revealed a large deposit of a dark substance believed to be lead. In the1800s, an English scientist found this matter to be some form of carbon. It was given the name graphite from the Greek word, "graphein," meaning “to write". The rest is history! Wood pencils were first made in process production in the 1600s. Although modern machinery and technology has helped speed up and simplify the process, the concept remains the same.
You may have been "misled" about pencil lead! The lead in pencils is not really made of lead—it's graphite mixed with other substances. To produce pencil lead, graphite is ground to a fine powder, mixed with clay and water, and then pressed together into thin rods at extreme temperatures.
If you were to glance at the flat end of an unsharpened pencil, it appears as if the outer wooden casing is one solid piece. That would require boring a hold down the center of the wooden dowel and then slipping in a rod of lead. Indeed, that is how the early pencils were constructed, but not in today’s mass production! The English method, which involved cutting a groove into the wood, laying a piece of graphite into the groove, and glueing a small slab of wood on top to encase the graphite, has been improved. Now, blocks of cedar are cut into slats and a machine bores grooves into those slats (they are half the depth of the graphite rod’s thickness). Next, the rods are put in place and a second grooved slat is adhered atop the first. After drying, these slats are cut by machine into eight pencils, varying in shape. After sanding the joints and applying numerous coats of paint, any imperfections are hidden and the pencils are ready to be distributed!
Have you ever wondered what the number printed on the side of the pencil is all about? It describes the hardness and darkness of the graphite it contains. The higher the number is, the harder the graphite will be. A hard core leaves behind less of the graphite’s tracings on paper, so the markings from it will be lighter than a softer core. That's why a #4 pencil's markings will appear lighter than a #2's, because less of the graphite is released. While a #1 pencil would be darker than the most-used #2, its soft core would tend to leave too much graphite residue, thus allowing for easier smearing and smudging.
The introduction of machine-graded tests, such as the standardized tests used in schools, set the standard for use of #2 pencils. If the lead was any harder than #2 lead, the markings would be too light for the machine to read and would therefore cause the inscriber to go over and over the same circle to darken it. This often made a hole in the test paper and rendered the results unreadable. If the lead was any softer than #2 lead, the markings would be too easily smeared which would also render the results unreadable.
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