DRAFTING PENCILS
Two types of pencils are used in drafting: wooden
and mechanical. The latter is actually a lead holder
and may be used with leads of different hardness or
softness.
Drafting pencils are graded according to the
relative hardness of their graphite lead. A pencil that
is considered soft is designated by the letter B. On the
other hand, a hard pencil is designated by the letter
H. Figure 2-1 shows 17 common grades of drafting
pencils from 6B (the softest and the one that produces
the thickest line) to 9H (the hardest and one that
produces a thin, gray line).
You will notice that the diameters of the lead
vary. This feature adds strength to the softer grades.
As a result, softer grades are thicker and produce
broader lines, while harder grades are smaller and
produce thinner lines. Unfortunately, manufacturers
of pencils have not established uniformity in grades.
Hence, a 3H may vary in hardness from company to
company. With experience and preference, you may
select the trade name and grade of pencil that suits
your needs. Selection of drafting pencils will be
covered in chapter 3.
45.672X
Figure 2-2.-Types of erasers.
ERASERS AND ERASING
ACCESSORIES
You must be very careful in selecting an eraser
that will remove pencil or ink lines without damaging
the surface of the drawing sheet.
A vinyl eraser (fig. 2-2, view A) is ideal for
erasing lines drawn on tracing cloth and films. An
ordinary double-beveled pencil eraser generally
comes in red or in pink color (sometimes called a
PINK PEARL). A harder eraser (sometimes called a
RUBY RED) (fig. 2-2, view B) is designed for erasing
lines in ink. The ART GUM eraser (fig. 2-2, view C),
made of soft pliable gum, will not mar or scratch. It is
ideally suited for removing pencil or finger marks and
smudges.
You can also use a kneaded eraser—the type
used by artists. It is a rubber dough, kneadable in
your hand, and has the advantage of leaving very
little refuse on the drawing sheet.
The so-called STEEL ERASER, shown in figure
2-3, is, of course, actually a scraper. It is used
principally for scraping off erroneous ink lines,
especially from tracing cloth. The figure shows a
short-bladed steel eraser; long-bladed steel erasers
are also available. A steel eraser is not generally
recommended for use by beginners because it has a
tendency to damage the surface of the drawing sheet.
Figure 2-4 shows an ELECTRIC ERASER. The
control switch is directly under the fingertip;
45.673
Figure 2-3.-Steel eraser.
45.674
Figure 2-4.-Electric eraser.
2-5
