Sand, 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.

SOURCE
The World Book Encyclopedia Chicago: World Book-Childcraft International, Inc., 1979

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This page was last updated on July 12, 2018.