The Mankato free press. [volume] (Mankato, Blue Earth County, Minn.) 1879-1924, 1883-05-25
How Window Glass is Made.


bottle by JOHN A. SAMBORN.
How Window Glass is Made.
To the uninitiated, sitting by the
window, tapping the pane idly as You
look through it, it would seem almost
an impOssibility to say that the win.
dow glass was blown, and yet it is all
simple enough when we have seen the
process.
Having seen bottles, ETC., blown,
my steps naturally took the direction
of the largest Of the window. glass
factories, and having obtained per.
mission from the Superintendent, we
were soon i'm what is known as the
furnace rOOm," where the main
work Of glass making, including the
blowing process. is done. 1t is u
novel sight. and one l shall not for.
get soon. The lurid light of the
many glowing furnaces. the quietly
but quickly moving forms of the
wOrklnen gliding around in and among
the shadows, made a sight that would
require only weak Imagination to
seem all but demonlacal. am hard.
ly well enough acquainted with the
art To describe the process infinitely,
and should any "boss blower" happen
to see this article he will please to
criticise me lightly.
To continue. First, be it known
that the glass of commerce Is com.
posed principally of white sand.
though arsenic, lime, a soda ash Of
some kind and some minor chemicals
in small quantities are essential. The
first step IS to free the sand from all
impurities. This is done by washing
it in huge watts. After being washed
and the compounds completed, con.
sisting of the various articles already
mentioned, the mixture is put into IL
huge crucible called 1.-THE pot" Yon
have all seen those little burned clay
crucibles jewelers. use. Well. this is
quite similar. only 1t is as large rs u
hogshead. This huge pot is lifted by
Il device quite similar to Il hook and
ladder truck, except that it has long
iron arms. lhe whole device being
OH wheels, tbs rolled into the furnace
room, and the pot placed in one OF
the ten huge furnaces. This opera
ton is called "placing the pot"
Under the intense heat of the furn.
ace, SO many degrees that l am afraid
to tell you (the fires never 60 out from
September LIST to July 3lst.) the mix
tuIe gradually melts, looking like
molten iron, only of a more whitish
color. The men called gatherers, as
their name implies, gather ball of
this liquid stand by dipping the pipe
into the crucible and withdrawing it,
allowing what clings to the end to
partially cool by slight contact with
warm water.
This process is continued until q
hall is gathered as large rs a water.
pail. This is then rolled around and
around in an iron howl until it as
sumes a pear shape. Then the ''blOw-
er" takes it, and now comes the hard.
est task in glass-blOwing. In start.
ing tins solid, red-hOt, half molten
mass to expand and assume a shape
something like our common glass, so
great are his efforts that his cheeks
expand to an enormous size and the
sweat starts out in huge drops. But
closely watching the half-transparent
glowing mass, you see little blubber
start in the center, and thus 1t
rapidly assumes Il regular demijohn
shape, say, two feet long by one IN
diameter. All this time it has been
rapidly revolved by the operator,
partaking shape from this iron bowl,
and having become sufficiently cool
and hard enough to bear lifting it is
by u nice movement swung upon d
crane and thrust into the furnace.
where, by the exact nicely of long
experience, it is kept in the intense
heat until half melted. 1t is then
withdrawn and swung 10y the opera.
tor from an elevated platform round
and round his head much as a profess
siOnal swings AN Indian club. mean
while forcing the air into it and sub
jccting it to the heat when necessary,
until he has red.hOt cylinder of per.
feet glass, exact in proportions, and
of uniform thickness, five feet In
the length and about fifteen inches
in diameter.
These are then allowed to cool, and
are cut to one exact length, by
a small cord Of molten
glass around the cylinder, allowing it
to harden, and then touching it with |
a cold iron, which causes the warm
CRYSTALS to contract so quick that it
cracks right off rs sOmOoth and even
rs Il carpenter could saw u board.
These cylinders are then cut length.
wise in the same manner. and are
then subjected to heated furnace,
intense enough to cause them to wilt
down perfectly fiat. This is called
the "liattening process" The sheets
are then revOlved around on an end.
less moving platform, something like
!. straw carrier of Il threshing ma.
chine, until cooled and tempered.
They are carried to the butting and
packing room, where they are made
INTO variOus.siZed sheets, or more
properly panes, to suit the demand,
and packed in manner familiar to
all and sent to all parts of the world.
To conclude, it might not be out of
the way to add that the factory
visited had twelve blowers. They
Ill belong to the "Glass Blowers
UniOn." and are permitted to blow
only so many cylinders day-ninety
being the number / believe. They
aaIn from $l25 to $3.50 a month, &C.
,ording to the number Of days they
work. But it is a fatal trade. The
poisonous gases, ETC., that they in
hale, more or less. renders long life
n the glass.blOwing business an i'm.
possibility. It is a rarity to meet a
glass blower over thirty-five years
Rochester Democrat.