The mirror., 1921-03-03

greater the proportion of clay the harder
the finished "1eads" and the smaller the
proportion the softer
The graphically mixture, when well
kneaded together, is nodded into leaves
and placed, while still plastic, in hydrau
lie presses. 1t is forced out of the presses
through dies of the size and shape neces-
sary to produce the kind of lead desired.
These dies are made of emerald, sapphire
or other hard minerals because softer ma
terials would wear away too rapidly.
AS the plastic mixture comes forth in
a continuous string it is cut to required
lengths, ordinarily about seven inches.
Compression in this process materially af-
fects the quality of the lead, that sub
jected to the highest pressures writing best
and giving most satisfactory all-around
service.
Finally the sticks of lead are baked in
furnaces. They are then ready to be given
their wooden cases which protect them
against breakage and provide a con-
venient grip for the writer's fingers.
Red cedar has been found the best wood
for pencils because it is close-grained,
whittles easily and is capable of high
polish. After being cut into slabs about
seven inches long, two and half inches
wide and a quarter inch thick the wood
is placed in kilns to remove excess mois-
ture and resin. The slabs when properly
dried are fed into machines which auto
matically cut six semicircular grooves in
one side of EACH
A stick of lead is placed in each groove
of slab and another slab, with glue,
brushed over its grooved surface is laid
on so that the six leads are covered above
and below with wood. The next opera
tion is performed by machine that cuts
the pencils out-six from each block-and
works them into the shape desired, round,
triangular hexagonal, etc. A sanding
machine then rubs their surfaces down
smooth. Some of the cheaper kinds are
given no further finish. The better ones,
however, are coated with varnish, plain or
colored.
In one of the vanishing processes most
generally used the pencils pass one at a
time through apertures in machine
which automatically gives a coat of var
nish to each as it goes through After the
first coat has dried sufficiently the pencils
are fed through the machine several more
times, being allowed to dry between coats
until the desired finish has been obtained
The more expensive ones get 10 or more
such coats. In another machine-varnish-
ing process the pencils, held in Frame
are immersed in pan of varnish apd
then slowly drawn out and dried. For
the finest finishes a final hand polishing
is given the pencils.
A machine now sands off the ends to
remove the varnish that has dried there
and sharp knives trim them smoothly.
Gold or silver letters may be stamped on
by laying on each pencil narrow strip
of gold or silver leaf and then bringing
it under heated steel die which makes
the leaf stick to the pencil under the let
ters on the die. By means of linked dies
letters may be printed much the same as
on paper, etc.
Nearly all of the pencils made in this
country are provided with rubber tips for
erasing. In the cheaper grades the rub
bers are glued into the wood with the
lead. The more expensive ones have metal
ferrules to hold the erasers. These fer
rules, made of nickel-plated brass are all
machine-made.
In the big factories the erasers are made
in great numbers, along with large
separate erasers, rubber bands and the
like. Eraser rubber, consisting of gum