For years, home cooks have been using Pyrex glassware and praising it for its versatility. The stuff seemed almost bulletproof until news stories that reported exploding Pyrex dishes began to circulate, causing many people to question the safety of their cookware for the first time. Although it's true that Pyrex is oven safe, it's not as indestructible as you may think. Stay safe by understanding exactly what Pyrex can and can't do.
What is This Stuff?
Pyrex is the brand name for a special type of glass developed by the Corning Glassware Company in 1915. Although Pyrex is much easier to say, scientists refer to this special product as borosilicate glass. This name is derived from the components used when making the glass.
Glass is typically made by melting silica and other natural compounds. Once melted, the glass gets molded into the desired shape, and then allowed to cool and harden. The glass produced by early glassmakers proved useful for a wide variety of applications but couldn't withstand heat, often breaking when used in lanterns and other similar tools. Tradesmen seeking a solution to this problem discovered that adding boron to the glass offered superior heat resistance.
Pyrex Temperature Capacity
The Pyrex heat capacity is truly impressive as the glass can withstand Pyrex temperatures up to 932 degrees Fahrenheit. The glass also tolerates extreme cold, remaining safely intact at temperatures as low as -313 degrees Fahrenheit. Because it's so tough, you can place Pyrex dishes in your oven, refrigerator or freezer.
Pyrex Has Limits
It's true that Pyrex will tolerate both hot and cold, but it can't do both at the same time. Pyrex can go from the freezer or fridge to the oven, but the trip needs to be a long one. Sudden changes in temperature can shatter any glass, including Pyrex. Exposing your Pyrex to sudden temperature changes will also void your warranty.
To play it safe, always allow cold Pyrex to warm to room temperature before placing it in your oven, and allow hot Pyrex to cool before going into the refrigerator or freezer. When removing hot glassware from your oven, always set the dish on a dry towel rather than in direct contact with your stove or countertop. Use dry potholders to handle hot dishes, as well, as contact with water or dampness can shatter hot Pyrex.
Never place Pyrex under your broiler or attempt to use it on your stovetop as both practices can cause breakage. Remember to always preheat your oven when using Pyrex, too. Some ovens kickstart the heating process by immediately producing large quantities of heat that can damage your glassware. If cooking food that will produce liquid as it cooks, add a bit of water to the bottom of your dish before placing it in the oven.
In Case of Accident
When users follow all of the safety instruction provided by Pyrex, shattering dishes are extremely rare. Breakage is possible, and like all glass, Pyrex may break if dropped or banged against a hard surface.
If you do break a Pyrex dish, wear shoes and thick gloves when cleaning up the glass. Pyrex often breaks into many small and very sharp pieces when shattered, so exercise extreme caution when handling broken shards. Inspect your kitchen thoroughly even when you think you're done cleaning—broken glass can sometimes travel farther than you think.
Always discard any food that was in a Pyrex dish when it broke. Shards of glass you can't see could make their way into the food itself and harm you or your dinner guests if consumed. Broken glassware is a good excuse to order a pizza.