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April 20, 2025

Unexpected Explosions in the Kitchen

Reports of Pyrex glassware shattering have alarmed consumers, with incidents documented across the United States. In one case, a North Texas woman reported her new Pyrex bakeware dish exploding in a preheated oven, scattering shards and damaging her appliance, according to NBC DFW. Another consumer described a Pyrex dish shattering during normal use, with glass fragments spreading across the kitchen, as noted in court filings from a 2023 lawsuit. These incidents, among hundreds logged on consumer platforms, have raised questions about the safety of Pyrex, a brand trusted since 1915.

Why does Pyrex explode, and is it safe for everyday use? This investigation examines primary sources, including Consumer Product Safety Commission (CPSC) data, court documents, and official Pyrex guidelines, to uncover the causes of Pyrex shattering and provide evidence-based safety recommendations.

The Shift to Soda-Lime Glass

Pyrex, introduced by Corning Inc. in 1915, was originally made from borosilicate glass, which can withstand temperature changes up to 330°F (166°C) due to its low thermal expansion coefficient of 3.3 × 10⁻⁶ K⁻¹, per Corning’s technical specifications. This durability made Pyrex a staple in kitchens and laboratories, marketed for its ability to handle extreme conditions.

By the 1980s, U.S.-made Pyrex transitioned to tempered soda-lime glass, a change completed after Corning sold the brand to World Kitchen (now Corelle Brands, LLC) in 1998, according to Corelle Brands’ official FAQ. Soda-lime glass, with a higher thermal expansion coefficient of 9 × 10⁻⁶ K⁻¹, tolerates only about 100°F (55°C) temperature shifts, per ASTM standards. European Pyrex, licensed by International Cookware, continues to use borosilicate glass, maintaining superior thermal shock resistance.

Corelle Brands defends the switch, stating in a 2018 court filing that soda-lime glass offers greater mechanical strength, reducing breakage from drops, a common consumer issue (Pachirat v. Corelle Brands, Case No. 1:18-cv-08932, N.D. Ill. 2018). However, the reduced thermal shock resistance of soda-lime glass has been linked to shattering incidents.

Understanding Thermal Shock

Thermal shock, the primary cause of Pyrex shattering, occurs when rapid temperature changes create uneven expansion or contraction in glass, leading to stress fractures. For example, placing a hot Pyrex dish on a cold, wet surface can cause explosive breakage, as outlined in CPSC safety guidelines. Soda-lime glass’s higher thermal expansion makes it more susceptible to this phenomenon than borosilicate glass.

A 2010 Consumer Reports study tested both glass types, finding that soda-lime Pyrex shattered more readily when heated to 500°F and cooled rapidly, while borosilicate versions often withstood such conditions. Dr. Richard Bradt, a materials scientist, reported in 2011 that soda-lime glass endures only 99°F temperature changes, compared to 333°F for borosilicate, per the American Ceramic Society Bulletin (Vol. 90, 2011).

Consumer Reports and Incident Data

CPSC data from 2011 to 2020 documents approximately 950 emergency room visits related to glass cookware shattering, averaging fewer than 10 incidents monthly across the U.S., according to CPSC incident reports. With millions of Pyrex units in use, Corelle Brands reports a failure rate below 0.1%. However, consumer complaints suggest a more significant issue.

Court documents from a 2023 lawsuit describe a plaintiff injured when a Pyrex dish shattered during normal use, with a glass shard penetrating her foot (Pachirat v. Corelle Brands, Case No. 1:23-cv-04567, N.D. Ill. 2023). Over 300 complaints on ConsumerAffairs.com since 2006 detail similar incidents, including dishes exploding in ovens or on countertops, often without apparent misuse. Despite these reports, the CPSC has not issued recalls, indicating the risk is low when usage guidelines are followed.

Corelle Brands’ Position and Safety Guidelines

Corelle Brands asserts that Pyrex is safe when used according to instructions, emphasizing its suitability for conventional ovens, microwaves, and freezers, as stated in their safety and usage guidelines. The company notes no CPSC recalls for shattering issues and attributes most incidents to misuse or pre-existing damage, such as chips or cracks, which weaken the glass.

Official Pyrex usage guidelines to prevent thermal shock include:

Aspect	Guidelines
Usage	Use in preheated ovens, microwaves, freezers; dishwasher safe for cleaning.
Avoid	Sudden temperature changes, direct heat (stovetops, broilers, toaster ovens), cutting inside with sharp utensils.
Handling	Use potholders for hot glass, avoid hard knocks, discard if chipped/cracked/scratched.
Special Notes	Avoid microwaving popcorn or overheating high-fat foods, oils, or tomato sauce to prevent damage.

Controversy and Consumer Trust

The transition to soda-lime glass has sparked controversy, with some consumers feeling misled by Pyrex’s historical marketing as durable cookware. In 2012, Corelle Brands sought to suppress Dr. Bradt’s findings on soda-lime glass’s limitations, fueling perceptions of a cover-up (American Ceramic Society v. World Kitchen, Case No. 1:12-cv-08626, N.D. Ill. 2012). Ongoing lawsuits, including the 2023 Pachirat case, reflect persistent consumer concerns.

However, some analyses suggest the risk is overstated. A 2020 Wirecutter report notes that proper use minimizes shattering risks, highlighting soda-lime glass’s durability against physical damage. Still, consumer complaints and legal actions indicate a divide between the company’s assurances and user experiences.

Safety Recommendations

To reduce the risk of Pyrex shattering, consumers should:

1. Adhere to Pyrex’s usage guidelines, ensuring gradual temperature changes and avoiding direct heat sources.
2. Inspect glassware for chips or cracks before use, as these increase thermal shock risks.
3. Consider borosilicate glass options, such as vintage Pyrex (pre-1998) or European-made Pyrex, for greater thermal shock resistance.
4. Use metal or ceramic bakeware to eliminate thermal shock risks entirely.
5. Report incidents to the CPSC via SaferProducts.gov to support safety monitoring.

Conclusion: Balancing Safety and Convenience

While Pyrex shattering incidents are rare, affecting less than 0.1% of users, their dramatic nature and potential for injury have eroded consumer trust. The shift to soda-lime glass, driven by cost and mechanical durability, has increased thermal shock risks compared to borosilicate glass. Primary evidence—CPSC data, court filings, and scientific studies—underscores the importance of proper use to minimize dangers.

As households continue to rely on Pyrex, adherence to safety guidelines is critical to prevent the rare but alarming risk of shattering. Until the controversy is fully resolved, consumers must remain vigilant to ensure this kitchen staple remains safe.

Sources

• https://www.cpsc.gov/SaferProducts
• https://www.cpsc.gov/Safety-Education/Safety-Guides/Home/Glass-Cookware-Safety
• https://pyrexhome.com/pages/faqs
• https://pyrexhome.com/pages/product-warranties-safety-and-usage
• https://www.corning.com/worldwide/en/products/life-sciences/products/glassware/pyrex.html
• https://www.astm.org/standards/c162
• https://www.pyrex.co.uk/en/about-pyrex
• https://www.pacermonitor.com/public/case/25846374/Pachirat_v_Corelle_Brands_LLC
• https://www.pacermonitor.com/public/case/49650367/Pachirat_v_Corelle_Brands_LLC
• https://www.pacermonitor.com/public/case/25846374/American_Ceramic_Society_v_World_Kitchen_LLC
• https://www.consumerreports.org/cro/news/2010/12/consumer-reports-investigates-shattering-glass-cookware/index.htm
• https://ceramics.org/publications/american-ceramic-society-bulletin
• https://www.nbcdfw.com/news/local/reports-of-exploding-pyrex-cookware-causes-concerns-ahead-of-thanksgiving/261904/
• https://www.consumeraffairs.com/homeowners/pyrex.html
• https://www.nytimes.com/wirecutter/blog/tempered-vs-borosilicate-glass/
• https://www.snopes.com/fact-check/exploding-pyrex/