Clear glass Pyrex kitchen utensils are practically an American icon. With their comfortable booklets and remarkable resilience, these famous boilers have been crucial when making biscuits, pots and pies since 1915. There is only one problem. About 15 years ago, the boilers began to explode when they became hot – which is ironic because the Pyrex glass was specially designed to be heat resistant. Some blamed a change in the glass formula and flocked to thrift stores to buy older models. Others cried hoax. Everyone agrees that exploding glass is bad.
Pyrex made headlines recently, as the parent company made a big move. Corelle Brands, the parent company of Pyrex among others, plans to merge with Instant Brands, the very popular Instant Pot manufacturer. The contract terms were not disclosed, and it is unclear how the merger affects any of the companies' products. But the news will remember that decades of old controversy with beloved glass pans, violent explosions and some gnarly injuries. Pyrex is also the subject of a trial in Illinois. In the court regulations, Pyrex's parent company Corelle Brands claims that a lack of events is due to customers using their products incorrectly. More on that case in a minute.
To understand the Pyrex controversy, one must look at the explosion reports within the framework of the glass's history. Not the entire glass history, but rather a series of innovations that started with Otto Schott, a German scientist who invented a new type of glass in the late 1
These dates are important because Corning's patent on the borosilicate glass used to make Pyrex boilers expired in 1936. At that time, the company developed a new formula for aluminosilicate glass, as it used to create a series of frying pans called Pyrex Flameware. (This line ended in 1979.) The real voice in the current controversy was planted in the 1950s, when Pyrex started making kitchen utensils from temperate soda lime glass. Corning licensed the Pyrex brand to a company called World Kitchen Now known as Corelle Brands-1998, and almost all accounts, all Pyrex kitchen items sold in the US after that year were made of temperate soda-lime glass. This is where the controversy really warms up.
Most glass products are made of soda-lime glass: window panes, jars, bottles, all types of glass. Soda lime glass is cheaper to do than borosilicate glass, which is without a doubt why Pyrex started experimenting with it. However, borosilicate glass is not only harder, stronger and more durable than soda-lime glass; It is also more resistant to thermal shock. Thermal shock is what happens when a temperature change causes different parts of a material to grow at different speeds, and the resulting voltage can cause the material to crack. If the temperature changes hands quickly, glass as material may explode or appear to explode. Resistance to heat shock is part of why Pyrex became so popular for kitchen utensils; You can move a hot glass pan to a cool place without worrying about it bursting or shattering. It is also part of why laboratories prefer to use borosilicate glass instead of conventional soda-lime glass. Pyrex kitchen utensils currently sold in the United States go through a thermal tempering process. In theory, this should strengthen the glass.
In practice, the difference between the performance of borosilicate glass and soda-lime glass is significant. When asked about the science behind the glass, Doctor John C. Mauro, professor of engineering and materials science at Penn State, said in an email that the thermal expansion coefficient (CTE) is the most important parameter used to measure heat shock resistance. A higher CTE number means that the material is less elastic to thermal shock. For example, Corning Vision's kitchenware, an antecedent to Pyrex Flameware, is intended for use by the stovetop and has a CTE near zero, Mauro explains. Borosilicate glass has a CTE of 3 or 4 parts per million per 1 Kelvin change (ppm / K). But soda-lime glass has a CTE of 9 to 9.5 ppm / K. "The beneficial properties of soda-lime silicate glass are that it is extremely inexpensive, but with a fairly high chemical durability and good optical transparency" Mauro explained. . "But soda lime silicate has a poor thermal shock resistance due to its high CTE. … borosilicate glass can withstand 2.5-3 times the temperature difference compared to soda lime silicate."
Mauro also knows his glass. Prior to taking his faculty position at Penn State, he spent nearly two decades at Corning, where he was one of the inventors of Gorilla Glass. It is worth remembering that Corning was the birthplace of Pyrex. Mauro has also co-authored academic papers on Pyrex's glass chemistry, and he is the editor of the Journal of the American Ceramics Society. Because of its extensive knowledge of the material, Mauro actually makes the science of soda-lime glass and heat sound even more dusty. He continued to note how the natural glass is tempered to improve strength. But this tempering process also makes the interior of the glass more compressed.
"So when it breaks, it breaks in a catastrophic way (that is, breaking into many small pieces, so-called" frangibility "), says Mauro." This contrasts with an untemped borosilicate glass that would break into much larger parts compared to a temperate soda lime. "
So perhaps appropriate, the transition from borosilicate to soda-lime glass was a big thing for Pyrex enthusiasts. Many believe that the new temperate soda lime glass is more likely to explode during temperature changes, a belief supported by some basic science, World Kitchen, the company allegedly responsible for the transition, insists that its tempering process is so good that the difference in glass type does not matter, meanwhile, Corning executives have since claimed that it made Pyrex of both borosilicate and soda-lime glass for several years before selling the brand to World Kitchen, which has not stopped Pyrex shoppers from sku ra internet, sale of real estate and thrift stores worldwide looking for borosilicate Pyrex. A website also points out how different graphics and origins are safer Pyrex products. (Protip: Look for PYREX graphics with all caps that can either indicate that it is vintage or it is from Europe where a company called Arc International owns the Pyrex brand and still makes its kitchen utensils out of borosilicate.)
How much better older (or European) borosilicate Pyrex is more recent soda-lime glass Pyrex is up for debate. Exploding Pyrex incidents have happened, as World Kitchen takeover, however. A surveyed consumer survey from 2008 showed some pretty gnarly accounts that people were doing simple things like putting a hot Pyrex pan in the oven just to cause it to explode in their hands and sending shields of glass into their attachments. There are also photos of the damage, so be careful not to click through the report. At that time, World Kitchen denied any responsibility in the incidents and explained that "explosion reports represent an extremely small proportion of the 370 million Pyrex rights on the market and are often the result of the consumer not reading the instructions or a consumer failing with a competitor's product for a Pyrex dish. "The company later disputed other aspects of consumer issues.
The risk of exploding glass pans is also not limited to Pyrex products. Other companies also make cooking utensils of soda lime glass, which would make these pans and cups more susceptible to crushing or cracking as well. Pyrex's parent company Corelle Brand-again, this is the company formerly called World Kitchen – said so much when we asked about the exploding kitchen utensil check.
"While some glassware is at risk of injury, Pyrex glassware has an exceptional security record," Corelle Brands spokesman said in a statement. "Based on reports made to the company and the Consumer Product Safety Commission, less than one-tenth of one percent of the Pyrex million products sold every year heat damage, and there has never been any recall of Pyrex glassware. "
Corelle Brands also confirmed that some of its kitchen utensils have been made from soda-lime glass since the 1950's, but when Consumer Reports conducted a survey In 2010, a Corning spokesman told the newspaper that several of its factories manufactured Pyrex from both borosilicate and soda-lime glass until Corning licensed the brand to World Kitchen in 1998. In other words, just buy Pyrex kitchen utensils before 1998 does not guarantee that it is made of borosilicate glass, and splitting is too a risk.
In an email, the CPSC stated that it has received 850 reports of split or exploding over the past seven years. "When compared to the millions of glass porcelain articles used in consumer homes, the number of incidents is small and the risk is low," explains CPSC-acting press secretary Patty Davis in an email.
But still exploding Pyrex incidents happen, and they continue to happen. After several reports of exploding and crushing Pyrex containers, Popular Science replicated an explosion incident in 2011 and shows in a video how small amounts of stress can lead to dramatic shortages of thermal shock. Not long after, researchers with the American Ceramic Society conducted a study called "Shattering Glassware Cookware", which reviews reports of incidents of exploding cooking utensils, namely what Pyrex did. The article's authors examined the actual glass itself and discussed the chemical and practicality between borosilicate and soda-lime glass. "Soda lime silicate kitchen utensils are the limit," they warned in their conclusion. "It doesn't seem satisfactory for all household cooking."
After the study was published, Pyrex's parent company, World Kitchen, sued the publisher of the article and its authors in the US District Court for the Northern District of Illinois. The company claimed that the scientific investigation made false and divergent statements about Pyrex kitchen utensils – especially its resistance to thermal crimes – and asked the court to suppress the paper.
It has now been over 20 years since Corning licensed the Pyrex brand, and complaints about the crime have recently been made to dispute. Several Pyrex customers who say they experienced exploding glass incidents themselves filed a class trial in June 2018, claiming that Corelle Brands does not warn consumers of the thermal fracture problem and then conceals warnings and warranties in the event. The court application details the arguments in the long run and also contains some troubled pictures. In December 2018, Corelle Brands submitted a draft decision. When asked about the trial, Corelle Brands said it did not comment on ongoing disputes.
But the explosions continue. About the same time, a class with Gizmodo, a Gizmodo employee filed an explosion himself after microwaving some bean beans in a Pyrex container for a few seconds. The container exploded, even though the glass screen was in the microwave oven. As far as she knows, she has followed all safety instructions, but the situation has no resemblance to the defect in Pyrex products that others have pointed out. Even small temperature changes can cause the glass to split or explode, and when that happens, the consequences can be dangerous.
It is difficult to draw conclusions from the ongoing Pyrex controversy, if only because we are not entirely sure how many non-events occur and under what specific circumstances. According to Corelle Brands, Pyrex's parent company, the incidents are rare and abusive. However, according to many consumers, the risks are poorly communicated, and the explosion can be unpredictable and dangerous. What seems crystal clear at a scientific level is that borosilicate glass is less prone to thermal shock as soda lime glass. It is also not difficult to find, especially if you can live without the Pyrex logo being stamped on the bottom of your forehead. Heck, Amazon Basics sells a pair of $ 15 borosilicate glass boilers. The equivalent Pyrex brand set made of hardened soda lime glass costs $ 22. And according to experts, the Pyrex glass can explode into small pieces. Uncommon as these explosions may be, they sound bad.
That doesn't mean you should throw away all your Pyrex kitchen utensils. However, you should follow the company's safety and usage instructions, which you will find here. Here is an important quote as a long list of warnings: "Avoid sudden temperature changes on your glassware." That means not pouring cold water on a hot Pyrex pan. Do not put a hot Pyrex pan on a cold marble bench. Avoiding such kinds of things is not exactly the other nature. But according to the rules, it can mean the difference between a deliciously cooked pot in an intact Pyrex pan and an oven full of glass slices and food pieces. We can all agree that delicious stew is better than crushed glass!