Pencil Hardness/ Softness
Ratings
By Doug Martin
November 3, 1997
Early pencils were made
using cut pieces of raw graphite dug from the earth. The hardness or softness
of these pencils was dependent on the quality or purity of the graphite, and so
was difficult - or impossible - to control. Different methods of refining and
mixing of graphite were experimented with over the years, but it was not until
about 1795 that a Frenchman, Nicolas-Jacques Conté,
developed a process for making pencil leads that is still in use today.
The process, known as the Conté Process, involves the mixing of finely powdered
graphite with finely ground clay particles and shaping and baking the mixture.
By controlling the ratio of clay to graphite, varying degrees of hardness can
be obtained, as well as fairly consistent and reproducible quality from batch
to batch.
The early Conté pencils were made in at least four grades, and a
numerical grading designation was used to distinguish them - 1 being the
hardest, 4 being the softest. As the Conté process
became known and used by other pencil makers, similar grading systems were used
by them as well. However, these grading systems were arbitrary and inconsistent
from one pencil maker to another.
In the early nineteenth
century, English pencil makers began using a letter designation
for varying hardnesses. Softer leads were designated
with 'B' (for black), harder leads with 'H' (for hard). Different schemes were
used to expand the range of grades, such as 'BB' and 'BBB' for successively
softer leads, and 'HH' and 'HHH' for successively harder leads.
By the beginning of the
twentieth century, a combination letter-number system had been established and
was in use by nearly all European pencil makers, and was also used for some
American-made pencils. This system is still in use today, and provides for a
wide range of grades, usually consisting of the series:
9H, 8H, 7H, 6H, 5H, 4H, 3H,
2H, H, F, HB, B, 2B, 3B, 4B, 5B, 6B, 7B, 8B, 9B
9H is the hardest, 9B is the
softest. At the same time, a number-only system was in use, particularly in the
#1 --- B, #2 --- HB,
#2˝ --- F, #3 --- H, #4 --- 2H
The common #2, or HB grade
pencil in the middle of the range, is considered to be the preferred grade for
general purpose writing. Harder pencils are most often used for drafting
purposes, while softer grades are usually preferred by artists.
American-made pencils can
often be found with numerically equivalent designations of 2-1/2, 2-4/8,
2-5/10, and 2.5, representing the same grade, but introduced by different
manufacturers to distinguish their products and to avoid patent lawsuits. It should be noted that no 'official'
standard for pencil grades has ever been adopted, and the designations are
still somewhat arbitrary and not always consistent from one manufacturer to the next.