What is Glass?
Glass is one of the most versatile – and most misunderstood – materials used in the world. Glass can be used for everything from eyeglasses to bottles, windows to the ‘glassphalt’ you find on the road. Many products called “glass” are actually ceramics and have entirely different manufacturing process than the glass we discuss in this article. Glass that is put into buildings or automobiles, in windows or on table tops is usually called flat-, float-, window or plate glass. The ancient Romans made flat glass by rolling out hot glass on a smooth surface. The resulting glass was neither clear nor even, but it was good enough to use in windows of the day. In fact, glass was quite a luxury at the time and only the nobility could afford it. By 1668, San Gobain had perfected a “broad glass” method of manufacture that involved blowing long glass cylinders, slitting them and unrolling them to form an almost-flat rectangle. This plate glass was then ground and polished on both sides. By the lat
Glass is sand with other ingredients added to make it melt easier. The fewer ingredients added, the higher the temperature it melts at and the less it expands and contracts. Almost pure sand would result in quartz, next down is borosilicate glass (Pyrex), lower down from there are soda/lime glasses (and can go lower than that: Sodium Silicate is a liquid at room temperature.) Handling glass batch requires safety practices including cleanup, keeping chemicals safely, and using a respirator.
Glass is an amorphous solid that has been around in various forms for thousands of years and has been manufactured for human use since 12,000 BCE. The status of glass as a liquid, versus a solid, has been hotly debated. The short story is that glass is a supercooled liquid, meaning that it is rigid and static but does not change molecularly between melting and solidification into a desired shape. Glass is one the most versatile substances on Earth, used in many applications and in a wide variety of forms, from plain clear glass to tempered and tinted varieties, and so forth. Glass occurs naturally when rocks high in silicates melt at high temperatures and cool before they can form a crystalline structure. Obsidian or volcanic glass is a well known example of naturally occurring glass, although it can also be formed by a lightning strike on a beach, which contains silicate-rich sand. Early forms of glass were probably rife with impurities and subject to cracking and other instability, b
