Glass by Machine
soda, and lime are the chief raw materials used
in making glass. Cullet is waste glass or
recycled glass that may be added to aid the
melting process. These materials are mixed
together and the resulting batch is sent to a
furnace where it is subjected to extremely high
heat until they literally melt together into
molten glass. From the furnace the molten glass
can be either blown, pressed, or drawn into the
desired shape(s). The shaped pieces are then sent
into an annealing oven, where they are reheated
and then cooled to strengthen the glass.
1 Blowing Glass Bottles Gobs
of molten glass are dropped through tubes in a
moving track. Iron molds move up and clamp around
the glass, and air blows the glass into the shape
of the mold. The bottle is released from the mold
and then annealed.
2 Pressing Glass Dishes Gobs
of molten glass are dropped directly into molds.
A plunger presses down on the glass, forcing it
to spread out and fill the mold. The dish is
cooled slightly, removed from the mold by
suction, and moved into the annealing oven.
3 Drawing Glass Tubing A
stream of molten glass is drawn around a rotating
cylinder. Air blown through the cylinder causes
the glass to form a continuous tube. The finished
tubing passes through the annealing oven and is
then cut into smaller pieces.
4 Drawing Flat Glass Sheets
of molten glass are drawn into a float bath
containing molten tin. Imperfections are melted
out of the glass as it floats in an even layer on
the tin. The finished sheet is then annealed and
cut into smaller sheets.
The World Book Encyclopedia
Chicago: World Book-Childcraft International,
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