The Democratic advocate., 1878-12-14
Process of Manufacturing Rubbers.

The first operation after receiving the
crude gum from the importer, is to cleanse
it. To facilitate this process the rubber.
which comes in Jumps resembling in size
and shape a soldiers canteen, is cut into
thin slices by means of large circular
knife, revolving with great speed and con-
stantly wetted. Then these slices are cut
into small pieces by means Of a chopper
a machine which resembles in its action
common hay y-cutter-and afterward the
pieces are reduced to minute particles in
another machine, which, at the same time,
washes out all the dirt and sand Beside
the accidental admixture of foreign sub
stances with the sap, the natives are in
the habit of throwing in sand and ashes
to increase the weight. The grit, unless
completely removed from the gum, will
show itself in the shoe, impairing its
smooth surface; and hence much Of the
fine finish depends upon the care taken at
this state.
The small particles of rubber, all clean,
are now shoveled into another machine
which rolls them together into rough
sheets. These sheets are then taken to
the drying-room, where they remain about
three months to admit of the complete
evaporation of the moisture. 1t is an i'm
portant point thoroughly to extract the
moisture of the gum, for if it is made up
into shoes before it is sufficiently dry, the
watery particles will expand under the
heat of vulcanization and cause blisters.
After the gum is sufficiently dry it is car
ried into the grinding room, and fed into
machines called grinders, where passing
between heavy iron rolls, heated with
steam, it is softened so as to permit of the
admixture of the vulcanizing material.
The call for low-priced goods has led to
extensive cheapening, by which less ex-
pensive material than rubber is added to
lessen the cost. Coal tar, lampblack and
other cheap and bulky articles are thus
sometimes used The gum is then run
into long sheets between calenders. The
sheets, as delivered from calenders, after
being cut into convenient lengths, are
carried to to the cutting machine and cut
into uppers and soles by means Of patterns
and sharp wet knives in the hands of skill
ed workmen. The uppers and soles are
now ready to be lasted. Meanwhile, in
another department, linings-whether of
of purple stocking net for shoes, or of wool
en- heecy cloth for "Arctics," or of heavy
felt for boots-are coated on one side with
rubber, by passing batch of gum in com
pany with the cloth between steel rolls in
another calender, and, after being cut into
various sizes, many thicknesses at once,
with dies in drop press, are distributed
to those who make up the boots and
shoes.
After affixing various strengthening
pieces of cloth-stiffenings, etc.-the rub
Der upper is carefully laid on sticks fast to
the rubber on the cloth, with light pres
sure and smoothing movement of the hand.
No pegging or sewing is required. The
edges are then trimmed, the sole is put on
and rolled down firmly, so as to adhere
closely in every part. The shoes are now
collected and carried to the varnish room,
where a coat of elastic varnish is quickly
applied, and the shoe, now of greenish
brown color, is hung in the the heater
This yarnish, beside imparting the luster
and finish, protects the rubber from being
injured by the intense heat of vulcaniza-
ton, and further protects the shoes when
in use from the effects of the atmosphere.
1t is found that goods which are made up
with dull finish, and not having the pro-
lection of the varnish, do not last so long
as the vanished goods.
The heater is large freproof room,
heated by means of large number OF
steam pipes. In the evening, when the
heater is full of goods, the doors are closed,
the steam turned on and the baking be-
gins. The heat is gradually run up to
nearly three hundred degrees, under the
supervision of experienced hands who re-
main all night carefully watching the
progress of the baking, as indicated by the
thermometers hung up inside but visible
through small windows in the wall Of the
heater. Too much heat renders the rub
ber brittle and rotten, and not quite enough
heat detains the sulphur in the shoe, and
causes its appearance afterward-when
they become what are called "white"
goods. These white or sulphurous goods
are really better to wear than those COM
pletely cured. During vulcanization the
gum becomes very soft and runs together
into one homogeneous mass, and finally,
when higher point is reached, it hardens
again. After remaining in the heater
sufficient time-about eight or ten hours
in all-the shoes are carried, at an early
hour in the morning, into the packing
room, where, after being removed from
the lasts, they are laid in long, glittering
rows on the table. Then comes along the
inspector, who examines every pair very
closely and passes judgment according to
the character ofthe workmanship.-4Tdde
Circular,