Up: Glassmaking
Sheet of Glass
8 of 23
|
|
| |
S H E E T G L A S S
CROWN GLASS. Until this century all sheet
glass processes were blown processes. In 1826, the date of the foundation
of Pilkington Brothers, the only known form of window glass was termed
"Crown" glass. By a method of blowing and spinning, the molten glass was
turned into flat discs or bullions. These bullions all have the blob of
glass in the middle, a characteristic of the old "bull's eye windows."
BLOWN GLASS. In 1832,
Messrs. Chance Bros. introduced a new process for making window glass from
the Continent, and in 1841 we followed their example. In this process
and the machine process which followed the glass is blown in the form of a
cylinder instead of a sphere.
The gatherer dips his blow pipe into the molten
glass inside the furnace. By means of a geared handle he is able to
rotate the pipe and accumulate a considerable quantity of glass on the end
of it. The pipe is withdrawn from the furnace and the gathering of glass
is dropped into a block lined with charcoal. The gatherer keeps it
rotating all the time and introduces compressed air at the top of the
pipe which starts the formation of the neck of the cylinder.
The neck is then formed and is distended by
blowing to the width of the cylinder which he wants, as shown in
Fig. 2, the main body of the glass remaining at the end
of the gather. The gather is now finished ready for the blowing operation.
The pipe is handed over to the blower who reheats the glass in a furnace
and then by swinging, rotating and blowing, he elongates it to the form of
a cylinder.
|
|
