Even casual pencil users wonder from time to time about the numbers and letters stamped on the barrel that indicate the grade of its graphite. There is more than one explanation for those familiar Hs and Bs, not to mention No. 1s, 2s, and 3s, almost to the point of being folklore. I’ve read that “H” means “hard” and “B” means “black”, but have also read that an “HB” lead can mean “half black.” At some point grade “F” was introduced, and I’ve been told that it can mean either “fine” or “firm”, and that it is roughly equivalent to a 2.5 in the number system. The way the following advertisement from 1913 reads, one might infer that it is the year that grade “F” was introduced, at least by the Eberhard Faber Co.
It gives no indication, however, as to why the letter “F” was selected. Further, the copy goes on to describe grade “F” as being a “happy medium.”
Without going into the history of the use of letter grades in education, one still has to wonder why no one thought that advertising a new product with a “grade” of “F” might be a bad idea. If this research is correct though, using “F” as a letter grade to represent failure had only been around for about 20 years up until that point, so perhaps its modern meaning hadn’t yet taken root.