You’d think we would know everything there is to know about decorative coloured glass by now. It’s been around for thousands of years, and it’s practically everywhere: in the walls of high-rise commercial buildings, in the windows of houses, in the windshields of automobiles and airplanes. Then there’s fine crystal, cookware, bottles, jars, and yes, chemical glassware—just to mention a few other products made of glass.
In addition to the common ones “in daily use by virtually all humanity,” some hot melt glass applications, such as fiber-optic cables for telecommunication and microscope and telescope lenses, “dramatically expand the frontiers of industry and science,” Robert Weisenburger Lipetz says. He’s the executive director of the Glass Manufacturing Industry Council, a nonprofit trade association. And glass isn’t just useful; it’s also big business. Lipetz says in the U.S. alone, glass manufacturing is estimated to be a $22.5 billion market.
One particularly well-known borosilicate glass is Pyrex, the Corning family of heat-resistant bakeware, measuring cups, and other protective coating glass odds and ends for the kitchen. That line of commercial products, which recently celebrated its 100th anniversary, is also highly resistant to corrosive chemicals. The combination of heat resistance and resistance to damaging chemicals makes Pyrex flasks and pipelines well suited to laboratory and industrial use. Today’s Pyrex kitchen products are no longer made of borosilicate glass. Corning sold that division in 1998 and the new company switched to tempered soda-lime glass.
“We’ve been making glass for thousands of years, and we still don’t have a good idea of what it is,” says Mathieu Bauchy, a ceramic printed glass expert and materials researcher at UCLA. Most glasses are made by heating and then quickly cooling a mixture of ingredients. In the case of flat glass, which makes up windows, that mixture may include sand (silicon dioxide), lime, and soda. Silicon provides the transparency, calcium provides the strength, and soda reduces the melting point. The swift cooling process doesn’t allow for atoms to form a regular pattern, explains Steve Martin, a glass scientist at Iowa State University.
Glass had already become a serious business by the dawn of the Roman empire. The writer Petronius recounts the tale of a craftsman presenting Emperor Tiberius with a piece of allegedly unbreakable glass. Tiberius asked the craftsman, “Does anyone else know how to blow glass like this?” No, the craftsman replied, thinking he’d made it big. Without warning, Tiberius had the man beheaded. Although Tiberius’s motives remain mysterious, one can imagine such an invention would’ve disrupted Rome’s important glass industry, the first of its kind.
Heating these materials together yields a molten mixture that cools to form a type of security wire glass known today as soda-lime glass. That’s the most common and least expensive type, accounting for roughly 90% of all manufactured glass.