Wichita eagle., 1888-08-26
HOW GLASS Is MADE.
THE PROCESS VARIES WITH THE
DIFFERENT KINDS.

1
Made-Colorfns Done by Metallic Oxides
Bottles and Window Glass-The Blow
Pire-Plate Glass.
The process of making glass is exceedingly
| interesting, but it is also elaborate and not
| free from complication. It can. therefore,
only be set forth in a brief and cursory NAM
| ner. So intricate Is the work in some of its
departments that one IS puzzled at the PRO
hclency in the art in ancient times. Tho
conclusion is forced upon Us that in this, as
In rsany other branches OF industry, the
| worknlen and artificers OF remote times were
in full command of many means and appli-
| ances Of which we are ignorant. The compo-
| sltion Of which glass Is made, not to mention
the fusing and finishing, implies a large
| amount OF chemical knowledge.
| What is this co1npcsitionl Generally, It
may be described as consisting Of certain
| number OF silicates, such as soda, potash,
lime, baryta, magnesia, aiumina and lead,
| the coloripg matter being obtained from iron,
nlagnesla, cobalt, uranium, copper or gold.
The composition, Of course, IS conditioned or
qualified by the kind of glass which is
wanted. The best glass is that which con-
talns the minimum OF uncombined silica.
Bohemian glass OF the harder kind contains
the silicates Of potash END Lime in predomi-
nant proportions; Of the softer kinds it con-
tains. IL addition, notable quantity Of the
aiicate OF aluInine. Soda and lime predoni-
nate in French plate. Potash and lead are
iihe principal silicates in the ordinary flint or
white glass. The lead gives density, soft
ness, feasibility and brilliancy. The exact
proportions, in different cases, Of the differ
ont ingredients belong to the secrets Of the
glassInaker's art
Tho process of manufacturing varies with
the different kinds Of glass. The first stepin
the process, however, IS the same with all
glass The first requisite is the melting pot,
the making Of which is an art by itself 1t
is made Of the purest kind of clay and con-
sists pretty nearly Of equal proportions Of
silicon and aluTnina. The mass, consisting
also often Of pieces Of old pots, Is worked up
with water and then laid aside for three or
four months It is after that time made4hto
pots-the work being Of the most particular
and 1aborious kind-covered at top and bot
tom, with an opening at the side. When
thoroughly dried and hardened in the fur
mace, the pots are filled with the prepared
material, called frit, mixed with O small
Quantity of cullet OF broken glass. After
some or ten or twelve hours, the heat of the
furnace having been brought to the highest
point, the pots are SKINNED and the melted
material is ready for what is called the jour-
ney. During the melting process the color
ing is done by means Of various metallic OK
ides. What is called flashed glass is pro-
duced by another and different process. 1t
IS only specifically colored. Pot metal,
when colored, is colored throughout
When the material is thoroughly melted
and skinned and made ready for tho journey
the work of the blower, or molder, begins.
Bottles and window glass-crown OF sheet
are made by the blow pipe. What is known
as plate gless and optical glass is cast; and
the glass used for heavy domestic utensils is
the result of combined process of blowing
and casting. The blow pipe to glass1naking
plays precisely the same part which is per-
formed by the potter's wheel in the manufac-
ture of earthenware 1t IS an iron pipe
smaller at the mouth end than at the other.
In the manufacture Of flint glass the pipe is
heated almost to redness, then inserted into
the pot Of fused glass which adheres to it.
By turning it round the workman gets as
much metal as he requires. He then distendS
the glass by blowing through the pipe, and
the glass being put into mold he continues
to blow until the desired shape is produced.
In this way bottles are made, and also almost
all articles for domestic use. Window glass
is blown into the form of cylinder. The
ends Of the cylinder are, after a cooling pro-
cess, cut of. The cyEner is then slit by
diamond from end to end, and. being again
heated, it is with much care and labor grad
ually flattened out.
Plate glass is made In different manner.
It is cast or pressed. When the material is
melted and ready for use the pot is lifted out
Of the furnace by means of forceps and
wheeled up to what is called the casting
table, where it is seized by q crane and
tackle, lifted and delicately poised so that it
can be easily tilted. Such is the necessity for
care and steadiness during the performance
of this task that tho men preserve absolute
silence. After having been poured out upon
the plato it is spread by means of steel
roller. By means of successive outpourings
and successive rollings the glass can be rlado
to any thickness. Where the machinery is
less complete the liquid matter is lifted with
q sort Of dipper, which, like tho blowpipe, is
brought first to q red heat. AS will be gath
cred from this description, the blowpipe Is
not needed in the manufacturing Of plate
glass. After the glass has been fattened out
anu brought 10 tne requisite StaNIa1C OF
thickness it is moved 20 the ennealing room,
and later it is subjected to an elaborate pro
cess of polishing.
Reference has been made to colored glass
and tho pot glass coloring hes already been .
explained Flashed glass, which has not yet
been explained, is thus produced: The work
man has two pots in equal conditions Of read |
iness-the one containing colorless materials, !
the other containing colored material He I
makes his first gatherings from the colorless
glass and the lest only from the coaored pot .
The consequence is that the glass when en- !
ished has q thin skin Of colored material on /
the outside For some ornamental purposes
this flashed glass is found specially useful.
Much that is interesting might be added
hero concerning the cutting, grinding and I
engraving Of glass, each Of which is prac-
ticed IN BROOKLYN, and practiced with skill
and success: but these belong TO the adornt1g ,
or decorating Of glass rather than to the
making OF it. Much also might be written
concerning glass paiuting--'J. L. W." IN
Brooklyn Eagle.