The next time you drink your favourite juice, look carefully at the cup. Is it made of glass? Look at the windows in your house. They are made of glass. Marbles are usually made of glass, too. Where does glass come from? Actually It’s mostly sand!
Glass is made by mixing sand with chemicals. The mixture is heated above 1430 °C. Coloured glass is made by adding chemicals. To make the sheets of glass you see in windows, liquid glass is poured onto melted tin and pulled onto rolled when it sets.
Glass containers were first made about 4,000 years ago. The liquid glass was built up around a piece of clay. When the glass hardened, the clay was removed. About 2,000 years ago, someone discovered that a gob of liquid glass on the end of a tube could be blown into a hollow shape – like your juice glass!
Today, most glass items are made by machines. Gobs of liquid glass are pushed into moulds. Others are formed by people who use fire to heat the glass and make it soft enough to blow.
Picture Credit : Google
