In the past several months, Consumer Reports has obtained 145 new reports of glass bakeware unexpectedly shattering, bringing to more than 300 the number of incidents we’ve reviewed. Among all of those cases, we found 60 reports of injuries, including cuts and burns. The new reports came mostly from readers sending in e-mails about incidents, following our article on glass bakeware in the January 2011 issue of Consumer Reports magazine. We also found an additional 24 reports from the Consumer Product Safety Commission’s new website, www.SaferProducts.gov.
The new cases we analyzed show that consumers continue to face instances of unexpected shattering with glass baking dishes, most occurring while being heated in the oven. The latest reports also include incidents involving eight glass bowls and seven measuring cups.
While hundreds of millions of dishes are used safely each year, we believe the situation deserves further investigation. We have asked the CPSC to conduct a thorough study of the glass bakeware on the market, with particular attention to the differences between bakeware made of soda lime and of borosilicate.
Most of the products, the consumers reported were made by World Kitchen, the Illinois-based maker of Pyrex in the U.S., and its competitor Anchor Hocking. Together they have more than 75 percent of the glass bakeware market.
Decades ago, Pyrex and Anchor Hocking made products out of a heat-resistant glass called borosilicate. Although it’s not clear when the switch occurred, their bakeware is now made of soda lime glass, which is less expensive to produce.
Borosilicate is still used to make glass bakeware in Europe, and for our January report, we put both types through extreme heat tests to examine the differences. You can see how we tested in the video below.
The test was contrary to the instructions on the back of the label. Our tests often go above and beyond manufacturer instructions. World Kitchen and Anchor Hocking state that the soda lime glass they use in bakeware is strengthened with a thermal tempering process. They say it is no more likely than borosilicate to shatter under sudden temperature changes but has greater resistance to breakage from impact, which they suggest is the more common cause of injury.