The Camden journal. [volume] (Camden, S.C.) 1866-1891, 1882-03-09
How Plate.Glass Is Made.

1t IH not very well Known tnat neariy
all the plate-glass so common nowadays
is manufactured on the other side OF
the ocean and imported here, though the
home business is protected by duty
$50 per cent. The manufacture Of plate
glass was in Europe originally con-
trolled by the royal families and the
process of its manufacture was royal
secret. At the present day the most
skillfu1 workmen in the factories OF
France and Belgium earn S., 900 year,
and consequently have no reason for
emigrating. AS rule the artisans that
do come here are inferior workmen.
Plate-glass is manufactured too hastily
here. The art is fine one, and the
utmost patience and skill is needed to
produce the finest article. The largest
plate-glass ever exhibited in this
country was that seen at the Centennial
in 1876. Its dimensions were twenty
two feet by ten feet six inches. 1t was
manufactured in France. This plate
in its entirety never had any practical
use, and was afterward cut up and
used. The largest plate made in this
country was nine feet in length.
The process of manufacture is very
long and tedious. The glass is melted
in large clay pots holding about a
thousand pounds of liquid each, which
is subjected to a very intense heat.
The most advanced manufacturers use
the "Siemens gas-burner, for the use
of which in this country very large
royalty is charged. The preparation OF
the pots is most important. They are
made of German or "Stourbridge "
clay, and to properly dry them from five
to six months are required. Unless thor
ougbly made there is liability OF break
age in the fire, involving the
los the pot and its con-
tents-a loss of about 500. When
the "batch" has been sufficiently
melted the furnace door is opened and
by means Of crane the pot is elevated
and the metal cast upon heated steel
table. Over the molten mass a heavy
roller is drawn which produces a level
surface. When partially cooled the
plate is pushed into a carriage
which has surface Of mortar. st is
then rolled rapidly into annealine
ovens, where it remains until it is proper
ly tempered. The glass is now what /!
commonly known as trough plate
glass;" and so much of it as is not suffi
GENTLY good in quality is subjected te
the further expense Of grinding ana
polishing and is sold for sky-ights ane
vault-lights. Now the plate is fit fol
grinding. The methods OF doing thi:
differ somewhat in different factories.
although the common practice is to pu
two plates of glass together and ther
move them rapidly one over the other
Very ingenious machinery is used in
England for the succeeding stages
The glass is cast usually of a thickness
tS1enah mon, astscessive
processes OF grinding is reduced to as
near one.quarter of an inch as possible,
If the surface is free from defects
and uniform when the thickness OF
three eighths OF an inch has been
reached, the plate is finished, as the
thickness is not Objectionable, although
cne-quarter Of an inch is the standard
The final polishing is done by hand,
and large numbers OF girls and children
are employed in many of the factories
for this purpose. It is not uncommon
that at this stage of the manufacture
az accident will break into fragments
the finished plate. The pieces are
gathered up and meltea over again to &C
through the same process. After com
pletion of the polishing the plate j!
carried to the stock-room and there
awaits its sale.