Glass is one of those everyday luxuries that over the years has become an unnoticed magic of science. Glass is used in every country, it can be found in every building and every car. Cellphones, tablets and computers use glass. Pretty much every facet of human life contains some form of glass. As you may know, glass is made primarily from sand, but how do scientists take a completely opaque material and transform it into a completely transparent material?
Glass is made by heating ordinary sand to the incredibly high temperature of 1,700 degrees Celsius or 3,090 degrees Fahrenheit, until it melts and turns into a liquid. When molten sand cools, it doesn't turn back into what you would imagine sand to be, it undergoes a complete transformation and gains an entirely different molecular structure. How ever cool the sand becomes, it will never return to a solid state. Instead, it becomes more of a frozen liquid or what materials scientists refer to as an amorphous solid.
In a modern commercial glass plant, sand is mixed with waste glass from recycling collections, soda ash, also known as sodium carbonate, and limestone, scientifically known as calcium carbonate and then heated in a furnace. The soda reduces the sand's melting point, but it alone has an unfortunate drawback -it produces a kind of glass that would dissolve in water. The limestone is added to stop that from happening. The resulting material is called soda-lime-silica glass. That's the everyday glass in your house and car.
Once the sand is melted, it is either poured into molds to make bottles, glasses, and other containers, or "floated", poured on top of a big vat of molten tin metal, to make perfectly flat sheets of glass for windows. Glass makers use a slightly different process depending on the type of glass they want to make. Usually, other chemicals are added to change the appearance or properties of the finished glass. For example, iron and chromium based chemicals are added to the molten sand to make green-tinted glass. Oven-proof borosilicate glass or more commonly known by its brand name Pyrex, is made by adding boron oxide to the molten mixture.
With the invention of modern glass being so long ago, its easy to forget just how amazing glass is. Could you imagine a world with no glass? It would be rather dark.
