A higher CTE number means the material is less resilient to thermal shock. But soda-lime glass has a CTE of 9 to 9. Mauro knows his glass, too. Before taking his faculty position at Penn State, he spent nearly two decades working at Corning, where he was one of the inventors of Gorilla Glass. Mauro has also co-authored academic papers on the glass chemistry of Pyrex, and he is the editor of the Journal of the American Ceramics Society.
Based on his extensive knowledge of the material, Mauro actually makes the science behind soda-lime glass and heat sound even more damning. He went on to note how soda-lime glass is tempered to improve its strength. However, that tempering process also makes the interior of glass more stressed. So perhaps appropriately, the shift from borosilicate to soda-lime glass was a big deal to Pyrex enthusiasts. Many believe that the new tempered soda-lime glass is more prone to exploding during temperature changes, a belief that is supported by some basic science.
Meanwhile, Corning executives have since claimed it manufactured Pyrex out of both borosilicate and soda lime glass for years before selling the brand to World Kitchen. One website even points out how different graphics and origins amount to safer Pyrex products.
How much better older or European borosilicate Pyrex is than newer soda-lime glass Pyrex is up for debate. Exploding Pyrex incidents have happened, since the World Kitchen takeover, however. An oft-cited Consumer Affairs investigation from showed some pretty gnarly accounts of people doing simple things like putting a hot Pyrex pan in the oven only to have it explode in their hands, sending scalding shards of glass into their appendages. There are photos of the injuries, too, so be careful clicking through to the report.
Other companies also make cookware out of soda-lime glass , which would make those pans and cups more susceptible to shattering or cracking as well. Pyrex parent company Corelle Brand—again, this is the company formerly known as World Kitchen—said as much, when we asked about the exploding cookware controversy. Corelle Brands also confirmed that some of its cookware has been made of soda-lime glass since the s.
However, when Consumer Reports conducted an investigation into the issue of shattering cookware in , a Corning spokesperson told the magazine that several of its factories were producing Pyrex out of both borosilicate and soda-lime glass up until Corning licensed the brand to World Kitchen in In an email, the CPSC specified that it has received reports of shattering or exploding in the past seven years.
But still, exploding Pyrex incidents do happen, and they keep happening. Following more reports of exploding and shattering Pyrex containers, Popular Science replicated an explosion incident in , showing in a video how small amounts of stress can lead to dramatic breakage incidents due to thermal shock. After that study was published, Pyrex parent company World Kitchen sued the publisher of the article as well as its authors in the United States District Court for the Northern District of Illinois.
The company claimed that the scientific research made false and disparaging claims about Pyrex cookware—specifically its resistance to thermal breakage—and asked the court to have the paper suppressed. World Kitchen ultimately lost the lawsuit on all counts. These early formulas were chemically weak however, often breaking down in water. Work proceeded to find the right proportions of silica sand and boric oxide that would continue to be heat resistant and chemically stable. In , an adequate formula was found.
These glasses, called borosilicates, were then introduced into lantern production. One of the original types of borosilicate glass introduced by the Corning Glass Works Company was brand-named Nonex. The potential for this product in the area of cooking was discovered in by Dr. Jesse T. Littleton who worked at Corning. He gave his wife a casserole dish made out of Nonex, the precursor to Pyrex. It worked as well as a ceramic cooking dish and a new era in cooking ware had begun.
The Nonex glass formula was revised to remove lead, and the ovenware was given to the Philadelphia Cooking School for more testing. A series of successful tests there led to the introduction of Pyrex ovenware in This same year the Corning Glass Works Company patented the formula and gave it the trademarked name Pyrex. It has been suggested that the term Pyrex was either a derivative of the word "pie" referring to its original use or the Greek "pyra," which means hearth.
In both cases, the "ex" suffix was used to give it brand-name similarity to Nonex. When World War I broke out, scientists who relied on German glass products found that the new Pyrex material met their needs for beakers, test tubes, and other laboratory glassware. Borosilicate glass has steadily been made more chemical, heat, and shock resistant.
It has also been applied to numerous products such eyeglasses, telescopes, and electronic components. Three classes of materials are used in making Pyrex including formers, fluxes, and stabilizers. Formers are the main ingredients in all glassmaking.
These are crystalline materials that, when heated high enough, can be melted and cooled to create glass. Fluxes are compounds that help lower the temperature required to get the formers to melt. Stabilizers are materials that help keep glass from crumbling, breaking, or falling apart. They are needed because fluxes typically destabilize glass compositions.
An ad for Corning Pyrex. Eugene G. Sullivan established Corning Glass Works' research laboratory in and set out with William C, Taylor to make a heat-resistant glass for railroad lantern lenses. The problem was that flint glass the kind in bottles and windows, made by melting silica sand, soda, and lime has a fairly high thermal expansion but poor heat conductivity. Both causing the glass to break.
Two solutions were possible: improve thermal conductivity or reduce thermal expansion. The formulation that Sullivan and Taylor devised was a borosilicate glass—a soda-lime glass with borax replacing the lime—with a small amount of alumina added. This gave the low thermal expansion needed and also had good acid-resistance, leading to use for the battery jars required for railway telegraph systems and other applications. The glass was marketed as "Nonex" for nonexpansion glass.
Littleton joined Corning in A physicist, Littleton knew glass absorbs radiant energy well, while metal mostly reflects it. Littleton took a cut-off battery jar home and asked his wife to bake a cake in it. He took it to the laboratory the next day. Littleton developed variations on Nonex and the result was Pyrex, patented and trademarked in May of Initial sale of Pyrex took place at the Jordan Marsh department store in Boston in By more than 4. In , Pyrex was introduced into the laboratory.
Laboratory glassware came from Germany but World War I cut off the supply. Corning filled the gap with Pyrex glassware, which worked so well that Pyrex replaced most other items. Today, Corning-style glassware is found in laboratories all over the world. The primary formers used for making Pyrex include silica sand and boric acid. Silica sand is also known as silicon dioxide. It is a crystalline material and was probably the major component of the first glass used by humans. Pyrex has a droplet in matrix phase structure.
The silicon dioxide creates the basic matrix. The borate material creates the droplets within that structure. It is the implementation of a semi-automatic machine Until now, the baby bottles were blown manually that helped increase efficiency in the factory. The arrival of electricity has revolutionized the way people cook. Ovens that run on gas-electricity or on coal-electricity were in full bloom.
The production of glass products was gradually reduced in Bagneaux-sur-Loing and the factory in Chateauroux quickly became the main production site. The company designs dishes that have a cubic form in order to fit in the microwave and gain space in the cupboards. A small revolution takes place during this period. The brand decided to change its strategy and the foreign markets that were normally led from France are now having new offices in Russia and Eastern Europe Ukraine and Poland in Approved by Michelin-starred chefs, the steam cooking technique started attracting cooking enthusiasts as well.
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