Glass contents a mixture of silicate and soda (i.e. Ca(OH)2, NaOH). Soda-lime composition is used to make bottle and plate glass. After prepared and measured the raw materials of glass, they are mixed and be fused initially. Then they are subjected to the coal-burning furnaces. The furnaces are full of heat, so the materials will be melted. The melted glass or the molten glass is brought to the correct working temperature, and then delivered to the forming machines. The molten glass will be formed into two forms, they are bottle and plate glass.
For making plate glass, the used method is pressing. In this process, the molten glass is produced by pouring molten on a flat surface and with double rollers on both sides of the molten glass. It will be smoothed on its both surfaces. By pouring glass into an iron table and rolling it flat. After annealing, the plate is polished on both sides. In polishing process, the temperature is high enough to make the plate glass perfect by removing fluid flow of the glass. The temperature is lowered as the glass through the end of the annealing oven.
Bottle is produced by two processes, pressing and blowing. Pressing is used to form the open side of the bottle. Blowing us used to form the body of the bottle. In blowing machine, the molten glass is dropped in a narrow and inverted mold, then forced down by an air blast into the lower part of the mold. A baffle then put over the top of the mold. The half-formed bottle, called a parison, is held by the neck, inverted, and then lowered into a second finishing mold, in which another air blast blows it out to bottle’s finished shape.
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