Time to start coveting vintage Pyrex

Pyrex is supposed to be tough stuff, capable of withstanding extreme temperature changes, like a trip from the freezer to the oven. And that was true with old Pyrex, made from thermal-stress resistant borosilicate glass. But starting in 1994, Corning began licensing the name Pyrex to other manufacturers, which, today, make Pyrex brand cookware with a different chemical formulation—soda lime silicate glass. A report in the Bulletin of the American Ceramic Society says the new glass doesn't have the heat-protection powers of the old stuff. So why use it? Apparently, the manufacturers say soda lime silicate glass provides better protection against breaking when dropped. The report didn't test that, but this could just be an example of chemical trade-offs. Listen to Scientific American's podcast about this news. Or read the full report. (Via Christopher Mims) Maggie