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Historical Materials: Drawing Technique
Modern Graphite Pencil
In handling and properties the graphite pencil most closely resembled the very early lead and lead alloy styluses. These similarities led to misnomers like lead pencil, and, because graphite made a darker mark, black lead. (1) Apropos of taking on its name, graphite eventually replaced lead point as the preferred dry drawing material and artists quickly began to find ways to place the cut and shaped chunks of high quality graphite into various holders. By the end of the seventeenth century wood-cased pencils with a graphite core were being manufactured for sale. (2) The most significant development in the production of graphite pencils occurred during the French Revolutionary and Napoleonic Wars when graphite exportation from England to France was halted. In 1793, Nicolas-Jacques Conté (1755–1805), a French engineer, was commissioned to design a pencil that would eliminate France’s reliance on the superior British graphite, as well as the German graphite pencil made with a mixture of (inferior) pulverized graphite, sulfur and glue. As a result of Conté’s invention the use of graphite pencil became widespread in the nineteenth century; indeed, Conté’s modern graphite pencil is the basis for the pencils we still use today: poly-grade leads that come in a range of hardness—the hardest leads to produce the palest grey lines; the softest leads to produce the deepest black lines.
Conte’s invention consisted of grinding the raw graphite into a fine powder—a process that was particularly important with inferior graphite as it helped to eliminate many impurities that could interfere with making a good pencil. The clean powdered graphite was then mixed with China clay (or potter’s clay) and water to form a paste that could be rubbed into molds. When dry, the molded leads were fired at a high temperature to create essentially a ceramic material that was quite brittle. Next, the leads were inserted into wooden cases so that they could be handled and shaped. (3) Wood cases were an earlier innovation to hold pure graphite, but became the most popular packaging method for the new fabricated poly-grade graphite pencils. (4) Hardness was a function of regulating the proportion of clay to graphite, and according to some sources, also varying the sintering (heating) time, temperature, and wax component. But the crux of the recipe relied upon the principal that a higher proportion of clay to graphite produced a harder lead and paler mark; a lower proportion of clay to graphite produced a softer lead and blacker mark. (5) To improve and modify performance other ingredients, such as shellac, rosin, gums, and most enduringly wax/oil, were sometimes added to the mix. Lampblack pigment was also added to bolster the softest/blackest leads. (6) Initially Conté graded his leads from 1 to 4 to indicate hardness, and numbers are still used for utilitarian pencil brands. Letters were introduced early on: H for hard and S for soft, although S was quickly replaced by B for black. (7) Initially the pencils were marked H, HH, HHH, HHHH and so on, and the softer leads were marked with the letter B in the same manner. (8) Today manufacturers of artists’ pencils use these letters combined with a number, B, 2B, 3B and H, 2H, 3H and so on. Appropriately, the grade in the middle of the scale is named HB and further refinement of the middle value leads include F, FF (or EF) and FHB, as grades between H and HB.
6. Watrous, 142.
7. Petroski, 118–19. Most of us can probably recall being told to use a No. 2 pencil when taking standardized tests.
8. According to Artists Material catalogues (1832–61) consulted for this research.
9. Petroski, 177.