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What those pencil lead numbers mean - and why “No.2” is the most popular.

https://upload.wikimedia.org/wikipedia/commons/3/3e/Closeup_of_pencil_graphite.JPG

The “No.2” on a pencil refers to how much graphite is inside its core. In the 1400s, humans used to write with pure graphite. But by the late 1700s, graphite had grows scare in Europe.

http://bernard.langellier.pagesperso-orange.fr/imgbiogra/desgenettes.jpg

So French chemist Nicolas-Jacques Conté invented a new recipe. Which is still what today’s manufacturers use. Instead of pure graphite, Conté baked a mixture of: powdered graphite + powdered clay + water. Manufacturers vary the amount of graphite they put in. Pencils with more graphite and less clay produce a darker line.

http://www.bluemaize.net/im/arts-crafts-sewing/graphite-pencils-8.jpg

To tell the difference, manufacturers have a grading scale: No.1 No.2 No.3 No.4 No.5. another popular grading scale refers to hardness – the more clay, the harder the pencil. The No.2 (HB) pencil is most common these days. Because it performed best with early scanning machines.

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No.1 smudged too easily while No.3 and No.4 were too light to read. One of today’s leading pencil manufacturers. Produces roughly 1.5 billion pencils each year. About 1 billion of those are No.2.

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