Not to be confused with PUREX
Pyrex (trademarked as PYREX and pyrex) is a brand introduced by Corning Inc. in 1915 for a line of clear, low-thermal-expansion borosilicate glass used for laboratory glassware and kitchenware. It was later expanded in the 1930s to include kitchenware products made of soda–lime glass and other materials.[1]
In 1998, the kitchenware division of Corning Inc. responsible for the development of Pyrex spun off from its parent company as Corning Consumer Products Company, subsequently renamed Corelle Brands. Corning Inc. no longer manufactures or markets consumer products, only industrial ones.
History
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PYREX glassware from Corning Inc. Newspaper ad showing PYREX bakeware from 1922Borosilicate glass was first made by German chemist and glass technologist Otto Schott, founder of Schott AG in 1893, 22 years before Corning produced the Pyrex brand. Schott AG sells the product under the name "Duran".
In 1908, Eugene Sullivan, director of research at Corning Glass Works, developed Nonex, a borosilicate low-expansion glass, to reduce breakage in shock-resistant lantern globes and battery jars. Sullivan had learned about Schott's borosilicate glass as a doctoral student in Leipzig, Germany. Jesse Littleton of Corning discovered the cooking potential of borosilicate glass by giving his wife Bessie Littleton a casserole dish made from a cut-down Nonex battery jar. Corning removed the lead from Nonex and developed it as a consumer product.[2] Pyrex made its public debut in 1915 during World War I, positioned as an American-produced alternative to Duran.
A Corning executive gave the following account of the etymology of the name "Pyrex":
The word PYREX is probably a purely arbitrary word which was devised in 1915 as a trade-mark for products manufactured and sold by Corning Glass Works. While some people have thought that it was made up from the Greek pyr and the Latin rex, we have always taken the position that no graduate of Harvard would be guilty of such a classical hybrid. Actually, we had a number of prior trade-marks ending in the letters ex. One of the first commercial products to be sold under the new mark was a pie plate, and in the interests of euphonism the letter r was inserted between pie and ex and the whole thing condensed to PYREX.[3]
Corning purchased the Macbeth-Evans Glass Company in 1936 and their Charleroi, PA plant was used to produce Pyrex opal ware bowls and bakeware made of tempered soda–lime glass.[4] In 1958 an internal design department was started by John B. Ward. He redesigned the Pyrex ovenware and Flameware. Over the years, designers such as Penny Sparke, Betty Baugh, Smart Design, TEAMS Design, and others have contributed to the design of the line.
Pyrex casserole dish with the 'Toledo' patternCorning divested itself of the Corning Consumer Products Company (now known as Corelle Brands) in 1998 and production of consumer Pyrex products went with it. Its previous licensing of the name to Newell Cookware Europe remained in effect.[5]
France-based cookware maker Arc International acquired Newell's European business in early 2006[6] to own rights to the brand in Europe, the Middle East and Africa.[7][8] In 2007, Arc closed the Pyrex soda–lime factory in Sunderland, UK moving all European production to France. The Sunderland factory had first started making Pyrex in 1922.[9]
In 2014, Arc International sold off its Arc International Cookware division which operated the Pyrex business to Aurora Capital for its Resurgence Fund II. The division was renamed the International Cookware group.[10] London-based private equity firm Kartesia[11] purchased International Cookware in 2020.[12]
In 2021, Pyrex rival Duralex was acquired by International Cookware group for €3.5 million (US$4.2m).[13][14][15]
In March 2019, Corelle Brands, the makers of Pyrex in the United States, merged with Instant Brands, the makers of the Instant Pot.[16] On June 12, 2023, Instant Brands filed for Chapter 11 bankruptcy after high interest rates and waning access to credit hit its cash position and made its debts unsustainable.[17] The company emerged from bankruptcy on February 27, 2024 under the previous Corelle Brands moniker, after having sold off its appliance business ("Instant" branded products).[18][19]
Trademark
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In Europe, Africa, and the Middle East, a variation of the PYREX (all uppercase) trademark is licensed by International Cookware[20] for bakeware that has been made of numerous materials including borosilicate and soda–lime glass, stoneware, metal, plus vitroceramic cookware.[21] The pyrex (all lowercase, introduced in 1975[22]) trademark is now used for kitchenware sold in the United States, South America, and Asia.[23] In the past, the brand name has also been used for kitchen utensils and bakeware by other companies in regions such as Japan and Australia.
It is a common misconception that the logo style alone indicates the type of glass used to manufacture the bakeware.[24] Additionally, Corning's introduction of soda-lime-glass-based Pyrex in the 1940s predates the introduction of the all lowercase logo by nearly 30 years.[25][22][26]
Composition
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A clear tempered pyrex soda–lime glass measuring cup produced by Instant Brands (left, differentiated by its different logo and bluish tint), and a clear borosilicate glass PYREX measuring cup produced by Corning (right)Older clear-glass Pyrex manufactured by Corning, Arc International's Pyrex products, and Pyrex laboratory glassware are made of borosilicate glass. According to the National Institute of Standards and Technology, borosilicate Pyrex is composed of (as percentage of weight): 4.0% boron, 54.0% oxygen, 2.8% sodium, 1.1% aluminum, 37.7% silicon, and 0.3% potassium.[27][28]
According to glass supplier Pulles and Hannique, borosilicate Pyrex is made of Corning 7740 glass and is equivalent in formulation to Schott Glass 8330 glass sold under the "Duran" brand name.[29] The composition of both Corning 7740 and Schott 8330 is given as 80.6% SiO2, 12.6% B2O3, 4.2% Na2O, 2.2% Al2O3, 0.1% CaO, 0.1% Cl, 0.05% MgO, and 0.04% Fe2O3.
In the late 1930s and 1940s, Corning also introduced new product lines under the Pyrex brand using different types of glass. Opaque tempered soda–lime glass was used to create decorated opal ware bowls and bakeware and aluminosilicate glass was used for Pyrex Flameware stovetop cookware. The latter product had a bluish tint caused by the addition of alumino-sulfate.[30][31]
Beginning in the 1980s, production of clear Pyrex glass products manufactured by Corning (and later Instant Brands, after the consumer division was spun off and renamed) was also shifted to tempered soda–lime glass, like their popular opal bakeware.[25] This change was justified by stating that soda–lime glass has higher mechanical strength than borosilicate—making it more resistant to physical damage when dropped, which is believed to be the most common cause of breakage in glass bakeware. The glass is also cheaper to produce and more environmentally friendly. Its thermal shock resistance is lower than borosilicate's, leading to potential breakage from heat stress if used contrary to recommendations. Since the closure of the soda–lime plant in England in 2007, European Pyrex has been made solely from borosilicate.[5][32][33]
The differences between Pyrex-branded glass products has also led to controversy regarding safety issues—in 2008, the U.S. Consumer Product Safety Commission reported it had received 66 complaints by users reporting that their Pyrex glassware had shattered over the prior ten years yet concluded that Pyrex glass bakeware does not present a safety concern. The consumer affairs magazine Consumer Reports investigated the issue and released test results, in January 2011, confirming that borosilicate glass bakeware was less susceptible to thermal shock breakage than tempered soda lime bakeware.[34] They admitted their testing conditions were "contrary to instructions" provided by the manufacturer.[31][35] STATS analyzed the data available and found that the most common way that users were injured by glassware was via mechanical breakage, being hit or dropped, and that "the change to soda lime represents a greater net safety benefit."[32]
Use in telescopes
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Pyrex glass used on the mirror of the Hale TelescopeBecause of its low expansion characteristics, Pyrex borosilicate glass is often the material of choice for reflective optics in astronomy applications.
In 1932, George Ellery Hale approached Corning with the challenge of fabricating the 200-inch (5.1 m) telescope mirror for the California Institute of Technology's Palomar Observatory project.[36] A previous effort to fabricate the optic from fused quartz had failed, with the cast blank having voids. The mirror was cast by Corning during 1934–1936 out of borosilicate glass.[37] After a year of cooling, during which it was almost lost to a flood, the blank was completed in 1935. The first blank now resides in the Corning Museum of Glass.[38]
See also
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Citations
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General and cited references
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Virtually unbreakable drinking glasses are made one of three ways; by tempering, annealing, or using a molecular infusion of glass and metal such as titanium. Each method produces extremely break-resistant glass drinking glasses. While no glass is truly “unbreakable” under high impact, glasses made using these methods withstand far more abuse than standard glass drinking glasses.
If you prefer real glasses over plastic drinkware, you’re in luck. There are many reputable glassware brands that craft extremely durable glassware and we’ve rounded up our top picks for you. All are proven performers in the restaurant and bar industry, so they can certainly withstand the knocks and bumps of any busy home. And being made of glass, they’re all dishwasher-safe and BPA-free, too.
Tempering is a heat-treating process that creates very resilient glassware and the closest thing to unbreakable glasses that you’ll find. However, excessive force and repeat impact can still cause tempered glasses to break. The most notable benefit of tempered glassware is ultra-strong rims and bases that resist chipping — even when stacked — making it popular for bar and restaurant use.
The Duralex factory in France invented the tempering process for glassware and its Picardie Glassware line of glassware sets is the top seller among tempered lines. It’s used in restaurants, cafes, and bars worldwide and also sold in retail sets for home use.
Bormioli Rocco is another major tempered glassware brand making resilient, nearly unbreakable heat-treated glassware. Again, tempered glass is not guaranteed unbreakable under unusual or repeated impact. But like Picardie, Bormioli Rocco tempered glassware is a proven player in restaurants and bars worldwide and available in retail packs for home use.
Libbey is another huge glassware manufacturer that makes a durable rim-tempered glassware line called DuraTuff, which has proven itself for years in busy bars and restaurants. Cardinal‘s Arcoroc line is another terrific tempered glassware line that’s made for restaurants and bars and is also available in smaller retail packs.
Annealing is another heat-treated process that produces durable, break-resistant glassware. Annealing glass involves a controlled cooling stage which reduces the molecular stress and fracture points common to plain glassware. The result is very durable glassware that, if broken, cleaves into a few large pieces rather than hundreds of razor-sharp shards.
Annealed glassware sets tend to be less expensive than tempered glassware so you can find it in several decorative styles and designs in Libby’s extensive foodservice line.
While both tempered and annealed glass are great choices for unbreakable drinking glasses, annealed glass breaks faster than tempered glass.
When tempered glass does break, it shatters into many small pieces. However, these aren’t sharp. This is why tempered glass is used for safety glass in windows, cars, and things like display cases. If you do happen to break your tempered glassware, it’s generally not dangerous, you just sweep it up.
Several crystal lines are using a newer process that combines titanium and glass at the molecular level. The result is a very strong lead-free crystal glass that supports lightweight, thinner-wall designs that are far more durable than plain glass or crystal. Many fine stemware and crystal manufacturers are using this method to enter the “unbreakable” glassware market.
Schott-Zwiesel and Spiegelau spearheaded the introduction of titanium- or platinum-infused dishwasher-safe crystal and many other top crystal glassware brands have followed suit.
The infusion process creates rugged, break-resistant glassware sets that withstand everyday knocks, bumps, spills, and even drops. That means it usually survives being tipped over on tables, shuffled about in the sink, and clanked in the dishwasher — situations where regular stemware and thin-walled crystal stemless wine glasses often meet their demise.
The infusion process doesn’t deliver the nearly unbreakable glassware that tempering creates. However, the result is far more durable than regular crystal glassware and fine stemware. Plus, titanium crystal products are completely lead-free, marketed as dishwasher-safe, and offer the same gorgeous clarity as classic lead crystal.
Silicone-wrapped glassware and portable glass water bottles offer another option if you prefer glass over plastic. Lifefactory Drinkware leads the charge with a huge selection of silicone-covered drinking glasses, water bottles, baby products, and kitchen storage containers.
If silicone-wrapped glassware appeals to you, you’ll also want to check out products from Ello, which offers a full line of silicone-wrapped glass drinkware, baking dishes and pantry storage similar to Lifefactory products. It’s always nice to have a few options!
Remember, “unbreakable glassware” isn’t truly unbreakable like many high-end plastic glasses. But, certain types of real glassware like tempered glass, annealed glassware, titanium-infused crystal — and the new silicone-covered styles — are far tougher and more impact-proof than standard glassware.
Not surprisingly, most unbreakable glassware options were originally designed for restaurant and bar use, and work beautifully in busy homes. If you like the durability of plastic, but don’t like the idea of using plastic glasses day-to-day, unbreakable and highly break-resistant glassware is an ideal choice.
If you want more info on proven glassware brands, head over to our review of the best drinking glasses. You’ll recognize a few names covered above, plus you’ll find more options for colorful, decorative, and specialty glassware.
Durability -- Very durable by glass standards, but don't throw it on the tile floor!
Styling & Finish - Gorgeous styles and finishes, many have a fine crystal look and feel
Dishwasher-Safe - Made for restaurants and hotels, so it's all great in the dishwasher
Price - $$ to $$$ - Very reasonable, stemware can be pricey but Amazon generally has great deals
4.8