Fig. 4 shows a prospective view of the block as it appears when taken
out of the form; the leads can be seen in the end. These blocks are fed
to machines which cut out the pencils in one operation. An idea of this
operation is given by Fig. 5, which shows a block half cut through. The
pencils come out quite smooth, but are sand-papered to a finer finish
before receiving the finishing coats. The finer grades of pencils are
given from seven to nine coats of varnish before being passed along for
the next process. Fig. 6 shows a pencil after it has been machined and
before it has been varnished and stamped.]
Furthermore, the requisite degree of hardness is obtained by the
subsequent operation, viz., the compressing of the lead and shaping it
into form ready to be glued into the wood casings. A highly compressed
lead will produce a pencil of greater wearing qualities, an important
feature in a high-grade pencil. Hydraulic presses are used for this
purpose; and the mixture of clay and graphite, which is still in a
plastic condition and has been formed into loaves, is placed into these
presses. The presses are provided with a die conforming to the caliber
of the lead desired, through which die the material is forced. The die
is usually cut from a sapphire or emerald or other very hard mineral
substance, so that it will not wear away too quickly from the friction
of the lead. The lead leaves the press in one continuous string, which
is cut into the lengths required (usually seven inches for the ordinary
size of pencil), is placed in crucibles, and fired in muffle furnaces.
The lead is now ready for use, and receives only a wooden case to
convert it into a pencil.
Where Does the Wooden Part of a Lead-pencil Come from?
The wood used in pencil making must be close and straight grained,
soft, so that it can readily be whittled, and capable of taking a good
polish. No better wood has been found than the red cedar, a native of
the United States, a durable, compact and fragrant wood to-day almost
exclusively used by pencil makers the world over. The best quality is
obtained from the Southern States, Florida and Alabama in particular.
The wood is cut into slats about 7 inches long, 2¹⁄₂ inches wide, and
¹⁄₄ inch thick. It is then thoroughly dried in kilns to separate the
excess of moisture and resin and to prevent subsequent warping. After
this the slats are passed through automatic grooving machines, each
slat receiving six semi-circular grooves, into which the leads are
placed, while a second slab with similar grooves is brushed with glue
and covered over the slat containing the leads. This is passed through
a molding-machine, which turns out pencils shaped in the form desired,
round, hexagon, etc. The pencils are now passed through sanding
machines, to provide them with a smooth surface.
How is the Color Put on the Outside of the Pencil?
After sand-papering, which is a necessary preliminary to the coloring
process, when fine finishes are desired, the pencils are varnished by
one of several methods. That most commonly employed is the mechanical
method by which the pencils are fed from hoppers one at a time through
small apertures just large enough to admit the pencil. The varnish is
applied to the pencil automatically while passing through, and the
pencils are then deposited on a long belt or drying pan. They are
carried slowly a distance of about twenty feet, the varnish deposited
on the pencils meanwhile drying, and are emptied into a receptacle.
When sufficient pencils have accumulated, they are taken back to the
hopper of the machine and the operation repeated. This is done as often
as is necessary to produce the desired finish. The better grades are
passed through ten times or more. Another method is that of dipping
in pans of varnish, the pencils being suspended by their ends from
frames, immersed their entire length and withdrawn very slowly by
machine. A smooth enameled effect is the result. The finest grades of
pencils are polished by hand. This work requires considerable deftness;
months of practice are necessary to develop a skilled workman. After
being varnished, the pencils are passed through machines by which the
accumulation of varnish is sand-papered from their ends. The ends
are then trimmed by very sharp knives to give them a clean, finished
appearance.
Stamping is the next operation. The gold or silver leaf is cut into
narrow strips and laid on the pencil, whereupon the pencil is placed in
a stamping press, and the heated steel die brought in contact with the
leaf, causing the latter to adhere to the pencil where the letters of
the die touch. The surplus leaf is removed, and, after a final cleaning
the pencil is ready to be boxed, unless it is to be further embellished
by the addition of a metal tip and rubber, or other attachment.
How is the Eraser Put On a Pencil?
In this country about nine-tenths of the pencils are provided with
rubber erasers. These are either glued into the wood with the lead, or
the pencils are provided with small metal ferrules threaded on one end,
into which the rubber eraser-plugs are inserted. These ferrules are
made from sheet brass, which is cupped by means of power presses, drawn
through subsequent operations into tubes of four- or five-inch lengths,
cut to the required size, threaded and nickel-plated.
[Illustration:
Courtesy of Doubleday, Page & Co.