The Pacific commercial advertiser. [volume] (Honolulu, Hawaiian Islands) 1885-1921, 1889-06-06
MAKING LEAD PENCILS.
DAILY CONSUMPTION BY THE cOUN.
TRY ONE-OUARTER MILLION.


TRY ONE-QUARTER MILLION.
Separating the Graphite Dust According
to Fineness-NIiHing the Clay and Fore
ing the CoiI-The Wooden Case and
Filling It.
The consumption Of lead pencils in this
country is estimated at 25O,O 900 a day. This
Is at the rate Of one per day to every leo OF
population, or about 100000 a year.
Graphite which is the softest substance dug
from the earth, is taken in the lump direct
from the mouth Of the mine TO the reducing
mill Here it is pulverized by stamps under
water, the particles floating of with the
water through a series Of tanks II comes to
the factory in Brooklyn in barrels, in the
form Of dust The powder is lusterleSs and
of a dingy color. II Is finer and softer than
any -four, and can be taken up in the hand
Just as water can, but IS hardly retained
more easily than water Is. II one attempts
10 take a pinch Of it between the forefnger
and thumb it Is as evasive as quicksilver,
and the only sensation left is that the flesh IS
smoother than before.
The first process in manufacturing Is to sep
arate the graphite dust further, according TO
fneneSS. IL Is mixed with sufficient water TO
run very freely. and Is then turned into
hopper, from which the water runs slowly
through a series of tubs. The coarsest and
heaviest particles settle 10 the bottom Of the
first tub, the next coarsest and heaviest in the
next, and so on, the movement OF the water
being made very gentle On reaching the
last tub, the powder, being twice as heavy as
water and sinking in il if undisturbed, has 50
far settled that the water discharged at the
top is nearly clear. After the flow IS stopped
and the powder allowed TO settle, the clear
water Is withdrawn by removing successfully,
beginning with the upper one, a number Of
plugs inserted in holes in the side Of each tub
care being used NOS 20 agitats the contents 50
az 10 disturb the deposited dust This being
done properly, the deposit Is removed through
the gates at the b.t-om Of each tue. The
separation Is thus performed, by This ingcn-
iCus process Of ~fO2,ug,' more perfectly than
it could by any CirssC laE ling, dry treat
h.ent being wholly impraotiraSle. Fcr the
haest pencils tie deposit from the last tub
only Is used, but for ordinary and cheap
grades that from the two before the last win
answer.
READY FOR TIE CLAY.
The graphite Is now ready for tn clay
This is "a peculiar pipe clay, from Germany.
after being subjected 10 the floating process
the finest Is mixed with the graphite, in pro
portions varying according TO the degree Of
hardness required The more clay used the
harder the pencil. For medium grades the
proportion Is about seven parts clay to ten
graphite, by weight. The graphite and clay
are mixed together with water, 10 the con
slstency Of thick cream, and the mixture is
fed % the grinding mills, which consist Of two
fat stones. about two feet in diameter. placed
horizontally, only the upper one running
Between these the mass Is ground ike paint,
FOR the finest pencils as many as tweuty-fOur
times, thus securing the most perfect strength,
uniformity and freeness from grit in the leads
After grinding the mass is incloSed in stout
canvas bags, and the clear water forced out
by hydraulic pressure until it becomes thick
dough.
1t then goes to the forming press. This Is
smply a small vertical iron cylinder, having
a solid plunger or piston driven by a screw
A plate is inserted in the bottom, having an
opening of the shape and size of the lead de-
sired, and the graphite is slowly forced
through the hole, exactly as water is forced
from a syringe, coihng itself round and round
ike a coil of wire on a board set beneath the
press. The coil is taken up at intervals, rove
OFF straight by the hands into lengths suffi
Gent for three leads, which are Strengthened
out, laid in order on a board and pressed fiat
by putting a cover over them They ara
finally hardened by placing them in a crucible
and baking in a kiln. The handling must lie
done expeditiously, as the leads begin drying
Immediately, and become brittle as they dry /;
but on first issuing from the press they are 50
plastic that knots may tIs ard lOOselyin them
-uSsunSEIs~zs, The WOODEs CASE.