The danger of using Pyrex glassware

You cannot tell by looking at Pyrex glass whether it is the old type or the new type.

Anyone who has ever used Pyrex measuring cups knows how durable they are. Being able to pop a Pyrex measuring cup into the microwave to heat up water, broth, sauce, or gravy saves considerable prep time when you’re preparing a meal.

Unfortunately, new Pyrex is not the same as our old tried-and-true Pyrex. Corning sold its Pyrex brand to World Kitchen in 1998 and the new company changed the formula. The old borosilicate glass was more heat tolerant than the new pre-stressed soda-lime glass. Both are consumer-grade tempered glass, both can break if used improperly, however the new Pyrex is less durable at extremely high temperature.

Our old Pyrex could withstand high temperature better, although it could still shatter at an extremely high temperature, much higher than we normally use when heating liquid. The new Pyrex can withstand high temperature, but shatters much more quickly with a rapid temperature change. You are more likely to break your new measuring cup by adding very hot liquid to the cold glass or by rinsing hot glass in cold water, as most people are apt to do.

The one fortunate thing about the new Pyrex is that it cannot withstand the rapid temperature change required for cooking crack cocaine. A mainstay of the crack kitchen is a Pyrex measuring cup. The crack cocaine industry must now buy or steal industry-grade Pyrex glass from laboratories.

You should use caution whenever you heat liquid to a high temperature in glass containers. Be extra careful when heating liquid in the new Pyrex measuring cups. If you do not know whether yours is the old Pyrex or the new Pyrex, err on the side of caution. The new Pyrex tends to shatter and spray small sharp glass pieces in every direction. All of the new Pyrex products including measuring cups, bake ware, and mixing bowls are now manufactured using pre-stressed soda-lime glass. has received many complaints. Be alert when using these products. It is worth extra caution in order to keep yourself and your family safe.

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