Conte's original process for manufacturing pencils involved roasting a mixture of water, clay and graphite in a kiln at 1,900 degrees Fahrenheit before encasing the resulting soft solid in a wooden surround. The shape of that surround can be square, polygonal or round, depending on the pencil’s intended use — carpenters don’t want round pencils that are going to roll off the workbench. The hardness or softness of the final pencil ‘lead’ can be determined by adjusting the relative fractions of clay and graphite in the roasting mixture. Commercial pencil manufacturers typically market 20 grades of pencil, from the softest, 9B, to the hardest 9H, with the most popular intermediate value, HB, lying midway between H and B. ‘H’ means hard and ‘B’ means black. The higher the B number, the more graphite gets left on the paper. There is also an ‘F’, or Fine point, which is a hard pencil for writing rather than drawing.
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