How to Make Glass

There are several steps to make glass. First, glass is made by melting together several materials at very high temperatures. The main ingredient that required is silica (SiO2) in the form of sand. Then, silica is combined with soda ash and limestone. Soda ash (Na2CO3) is added to reduce the sand's melting point. Limestone (CaCO3) is added to make the glass water-resistant. The combination of these materials is called the 'batch'.
Then, the batch is melted in a furnace at temperatures of 1700°C (3090°F) for 5 or 6 hours and being frequently stirred during the process. After the batch becomes liquid or becomes molten glass, it can be formed into the desired shape.
Molten glass can be formed into two shapes. The first shape is plate glass. Plate glass is made by pouring molten glass into a melting pot upon a table covered with copper. Then, the molten glass is rolled or flattened out to a proper degree of thickness.
The second shape is bottle glass. Bottle glass is made by placing a piece of molten glass on the end of a blowpipe. After that, the molten glass is expanded by blowing air into the pipe. The removable mould is placed exactly under the blowpipe. When the air is blown, the molten glass follows the shape of the removable mould and forms the bottle glass shape.
Finally, when the piece is finished, the glassworker puts it into an annealing oven where it is gradually cooled over several hours to several days.

Isabella Widuri
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