If you, as I did, grew up trusting Pyrex cookware as essentially indestructible and capable of handling stove to counter to freezer all in one go, well, have I got some news for you.
Pyrex was Pyrex because of its makeup: it was, for most of our lives, borosilicate glass (and in fact came to be shorthand for borosilicate glass). Most kitchenware is soda lime glass, and it’s soda lime glass that is infamous for shattering if, say, you take a casserole out of your oven and put it directly on a stone countertop. It’s very vulnerable to thermal shock, and can even shatter with no small amount of violence when it happens.
Borosilicate glass is much, much more resistant to this sort of thing — you can literally take it from a 500 degree oven and put it directly on a wet, cold countertop with no ill effects. This is why people loved Pyrex. And this is why it’s a goddamn ridiculous, obnoxious, idiot marketer decision for someone to make Pyrex out of something other than borosilicate glass, but that’s just what “World Kitchen” did when they bought the brand name from Corning in 1998. Pyrex today is soda lime glass, not borosilicate, and Consumerist shows us what that means.
It’s a shocking breach of trust for this goofball firm to make Pyrex that, fundamentally, isn’t Pyrex, but that’s what happens when you get people who think of “branding” as more important than actual goods.