How Is Glass Made?
Ordinary glass is made from clean, white sand and two white, powdery chemicals known as soda and lime. Just plain sand can be made into glass, but it must be heated to about 3,000 degrees Fahrenheit. It’s both difficult and expensive to bring a substance to such high heat. It’s also possible to make glass by adding sand to sodium carbonate and limestone.
After those materials are mixed together, they can melt at a lower temperature to make glass. Other glass-making ingredients can include alumina, lead oxide, salt-pet-re and zinc oxide which are used to make different types of glass. In the production of plate glass, waste glass from a previous melt is also added, making up 5 to 40 percent of the mixture.
In a glass factory, the glass ingredients are heated in a large furnace at high temperatures until the mixture becomes thick syrup. When this syrup cools, it is glass. While the glass is still in a melted state, it is shaped into many useful things. Machines roll the hot glass into flat sheets for windowpanes. Other machines mold, blow and press gobs of molten glass into bottles, drinking glasses, light bulbs and other glass objects.
To make objects like vases, craftsmen blow into a glob of liquid glass with the help of a long tube. Glasses, window panes, mirrors are few of the many things that are made from glass. Glass is not only useful, but can look beautiful too. Windows made of stained glass are works of art.
Plate glass made by rolling: Sand, lime and soda are heated together in a furnace to make liquid glass. Rollers are used to flatten glass into sheets, which are first cooled, then cut.
Plate glass made by floating: Liquid glass from a furnace is floated and slowly cooled on the surface of liquid tin. After the glass has cooled down, it is cut into pieces.
Handmade glassware: Vases, ornaments and other intricate glass objects are made by a glass-blower. The glass-blower uses a metal blowpipe which has a glob of hot glass at the end of it. A glass blower then blows the soft glass into shape.