PYREX vs pyrex: What's the difference and why it matters?

[TheBlackAdder]

Glass cookware from the PYREX and pyrex names is indeed different, and one may or may not be made with borosilicate glass rather than soda lime. But what you think you know about PYREX might not be true. In this video, chef and food writer Matt Degen clears up the confusion.

Old school PYREX is now made in France and still contains the costlier borosilicate glass making it more expensive.

New pyrex does not contain borosilicate, and is instead made out of soda lime glass which is cheaper.

What's the difference -- thermal shock, the ability to tolerate extreme changes in temperature.


UPDATE: But the mystery continues as the upper and lowercase spelling does not definitively identify which glass the products are made from. Even Corning cannot answer that. A mineral oil test can help identify they type of glass, but that is not definitive either. The best advice from the chef is the lowercase pyrex is not borosilicate. If you are in Europe, it's all borosilicate. There are other brands that use borosilicate. If you find PYREX in the US with Made in France... it's probably borosilicate. The chef prefers vintage Corningware, made from pyroceram with properties that even PYREX cannot meet.