Perrysburg journal. (Perrysburg, Wood Co., O. [Ohio]) 186?-1965, 1869-05-28
How Window Glass Is sade.


Monthly for Nay.
How Window Glass Is MADE.
A PANR of glass is rot complicated |
structure. Were an inventor, however, |
called upon to devise q method of making |
window glass, having no previous &C.
Quaintance with the subject, the method |
in use would seem to be the very last he |
would be likely to hit upon. II is usual |
to speak of common window glass ss be |
ing blown. To one unacquaiuted with |
the mode of its manufacture, the term |
blown contains very imperfect idea of |
it. 1t is true that blowing is a large and |
important part of the operation. but it |
would be impossible to produce a fiat pane |
of glass by blowing alone.
There are three ways in which nat Ia |
bles or plates of glass may he obtained, |
one of which does not involve blowing at |
all. Glass made by the latter process is
called plate glass. The glass made by
the two systems which require blowing
are called respectively "crown glass and
"cylinder glass" terms derived from pc
culiarities in the methods of producing
them. We shall first describe the method
of producing crown glass.
The arrangement of the furnaces for
manufacturing glass has already been de-
scribed. The workman takes up ON the
end of his pipe large mass of glass by
successive operations exactly as described,
except that for making crown glass he
takes up a much larger weight lie also
rolls 1t upon the "marver" in the same
manner AS he would for making bottles
but in the present operation greater care
is required to prevent the occurrence of
inequalities, as the mass of plastic glass
is so much larger. Having formed the
| ball upon this mArver until it assumes the
shape of pear, it is next softened in =
small furnace, and again rolled an the
marver TO correct any inequalities that may
have formed during the latter heating, and
at the same time TO collect the greatest
mass of glass Vt the extreme end, techni-
caly called the bullion" The bulk is
now further extended by blast from the
lungs of the workman, it being meanwhile
supported by resting the pipe upon n
horizontal bar, called the bullion bar"
until it assumes nearly the form of n
sphere. In some instances the "bullion
bar is dispensed with, other equivalent
apparatus being substituted for it. Its use
is to aid the workman in rotating the
bulb, so us to keep it as nearly rs may be
to the globular shape.
1t is next taken to the bottoming hole
This is acircular hole in furnace, before
which, at short distance, is built up q
screen of mason work, which extends far
enough to protect the workman from the
heat. His face is also protected by mask,
having apertures with glass plates to per
NIT his seeing his work. The pipe with
its expanded bulb is laid across u hook
projecting from the screen of mason work.
Here the bottom of the bulb (bullion) is
exposed directly to high heat, and the
pipe being rapidly rotated by the work
man, the centrifugal force thus generated
soon reduces the bulb from the form of a
globe to that of a prOlate spherOid-that
is, it spreads laterally until the side Oppo-
site the fire becomes nearly fiat. An AS
sstant now attaches to the centre of the
side opposite the pipe an iron rod called
"pontil" or "punty," so that it shall
stand as nearly as possible in the axis of
rotation. The first workman then imme
diately detaches the pipe by touching the
neck of hot glass with a cold iron wetted
with water. The side to which the pipe
T has hitherto been attached is now pre-
, sented to the furnace. Rotation being
continued, the glass begins to expand, the
hole left by the detachment of the pine
becoming larger and larger, until finally
the whole bulb suddenly expands into a
single fiat table. Before this result is at.
tained, however, it becomes necessary to
/ remove the bulb to large furnace called
the flashing furnace" which has an
opening similar to the bOttoming hole, u
r except that it is larger The glass has
3 now the form OF fat circular plate, but
at the point where the punty is attached
D.. there will be left upon it projection
called the "bul's eye" In order that the
;, form of the plate may not be altered, rota
! tion is kept up until the glass is sufficient
e ly cool 10 support ITSELF 1t is then takeI
; upon large iron fork by another assist
5 ant, and, the punty being cracked of, tht
plate is carried to the annealing furnace
Q where it remains twenty-four hours. Al
a ter the annealing, the glass may be Gu
I into proper sizes and packed.
=. The above outline gives but faint idei
|, of the skill required to produce crown
glass. Necessarily description of all tht
o minor nanipulatiOns requiring the great
est dexterity have been omitted. Enough
' however, has been said to give the reade
n correct ideas of the general principles o
c the method. Crown glass is not manufsc
tured now in this country or in Europ
Q as extensively rs cylinder glass.
:; In the manufacture of cylinder glas
1, the blowing extends only so far as to pro
Y duce cylinder open At both ends. II
fact, the blowing is, during the entire pro
q cess, accompanied by manipulations of
!: peculiar character blowing alone woul,
not produce the desired result. The fur
n mace holes are somewhat elevated, an
8. platforms extend out from the base of III
T. furnace, one from each hole or pot, upol
/. which the workmen stand. These plat
e, forms are of considerable length, and nav
c. pits of considerable depth dug betwee
r, them to permit the workmen TO swing tn
!" bulb during the process Of elongatloI
IS The manipulatiOns are the same as 70
crown glass up to the point where tn
" globe is expanded, and have so far bee
8, already described. When the blast is fir!
h forced into the plastic glass, the expansio
It takes place in that portion of the pea
8. shaped mass called the neck. The worl
e man now holds the ball over his head, an
| the weight OF the thick portion Of th
ID mass presses down the expaned portion VI
til it assumes the shape Of the top of bo
10 tie, like the large ones used by druggists
Of contain their tinctureS, etc. The expanC
ed portion being now permitted TO COO
n. which it does rapidly on account OF i
IS, thinness, becomes rigid. The workma
r. then commences complex manil
ulation He blows through the piI
at the same time he rotates IT
8. keep up the cylindrical form Of II
it expanding portion, and also swings T.
in ball in one Of the pits above describe
in thus elongating the cylinder. The gla
ed as It becomes thin cools OFF and becom
d. rigid, and one of the most difficult par
~ or the operation consists in expanding u
"a glass 10 the required size az precisely d
lu time when il becomes 50 cool as to rema
m ! in the r,rOnpr form When the y-alls 4