The Fairmont West Virginian. (Fairmont, W. Va.) 1904-1914, 1906-02-27
BLACK LEAD PENCILS
THEIR MANUFACTURE AND THE MA
TERlALs THEY CONTAIN.

The Plupbaao Comes Mainly From
Bavaria and the Red Cedar Wood
From FIOrida--How the Graphite Ia
Manipulated to Form the Leads.
The first pencils in the modern sense
were simply pieces Of pnro nlumbago.
the more common name Of which is
black lead or graphite. This mineral
has always been rare, and as the very
qualities Of softness and bIackness
which made It good to mark with made
It also disagreeable to handle it was
not long before covering Of wood WAS
provided, partly to protect the hand
and partly to economic the plumbago.
Tho best graphite in the world has
been taken from mines in Borrowdale,
England, and in eastern Siberia. The
quality in both places was such that
solid slabs Of it could be sawed out
and these In turn cut into the slender
strips which form the leads Of mod.
ern pencils. The quality, however.
was not sufficient to permit this meth
cd to be adopted exclusively. The
Borrowdale mines indeed have long
since been exhausted. Most Of the
graphite now comes from Bavaria.
Plumbago for the best pencils now
undcrgoes number Of processes. It is
minedt in irregular Jumps or in any
form in which 1t may be got out most
cheaply. Shipped to the pencil fac
tory, 1t is there ground and mixed with
finely pulycrlzed clay in quantities
which depend upon the hardness or
softncss which the pencils are to pos
sess. For hard pencils, such as are
used by mechanical and architectural
craftsmen, the mixture is ono part of
plumbago to two parts Of cIay. The
softer the pencil the greater tue pro-
portion Of pumbago.
The mixture is "thinned" With wa
ter and repeatedly ground until It is
perfectly smooth and free from grit.
1t is then placed in canvas hugs and
squeezed by machinery until enough
water Inns been removed to leave u
tenacious, dOughltke mass. from which
the leads are to be formed.
The dough" as it is called, is
placed IN a strong steel cylinder, one
end Of which is perforated with holes
OF the same size as the leads which II
is desired TO make. The pressure Of q
slowly descending piston forces the
dough out through the holes in long
strings. which are quickly removed
and laid IN groovel or on cleltcd
boards to slulghten and dry.
Tie next stop is the temperlng Of the
leads by heating to a red heat in cru
clblcs. by This process the hardness
or softness Of the pencils is Sill fur
Their modified Impurities are burned
out and tho little strips OF plulnbago
are considerably strengthened They
ARE now ready for their wooden cases.
These In all the better grades Of pen
ellis are r!aGe OF red cedar, most Of
which comes from FlorIdn. This wood,
better than anything else, answers tho
requirements OF softnrss aud straight
ness Gf grain and perulanency
Tile wood il sawed. by machinery
into strips, two Of which when placed
together nre equal to the diameter OF
the pencil. But IL tic lead Is to be
square the two strips are not Of equal
thickness. That which contains the
groove for Tic lend is the thicker. Most
pencils, however, have round leads,
ana In this case the two strips ire OF
equal thickness, and each contains n
semiclrcular groove.
Tho lead Ii now Inserted In tho
groove ind the two strips Nrc glued
together. When dry, they arC passed
through Il clrculNr cutter slmllar to the
so called hollow bits by which The ends
Of ladder rllDgs are rounded and dow
els are made, They emerge ut tue
other end perfectly rounded, Nothing
remains but cutting tho sticks into.
suitable lengths, painting or polishing,
mad stamping With the makers hume
and the degree of hardness
Pencils made 8pf the pure graphite
would not iba superb 30 those 40 Which
sthe graphite nfxed with div me
mo- iefn ien0Ils poss esa not ohly egeais
5et sttength iibut there ate lever fItty
Spots and they correspond more regu4
iarls ID tiie'mafks which IRE lturnpea
upon ttiem. Edward Wiliiston i'rentz
la YOulhsa eomnnnion.