A friend forwarded an email item blaming the Chinese for a recent baking dish shattering problem with Pyrex glassware. I looked into it, and found that there really is a problem, but that it was American in origin!
Pyrex was originally a trademark of Corning glassworks for a borosilicate glass very resistant to thermal shock. That word Pyrex became a synonym for borosilicate glass throughout the English-speaking world. Bakeware made of borosilicate glass really is quite resistant to shattering when moved in and out of cooking ovens, although it is not "invulnerable".
In 1998, Corning sold off its kitchenware operation. After a chain of ownerships, that operation has become World Kitchen, headquartered in Rosemont, Illinois. It has offices and manufacturing operations pretty much around the world. World Kitchen still uses the Pyrex brand name for its glass baking ware, as well as for laboratory glassware.
What I found is that laboratory glassware worldwide with the Pyrex name is still made of borosilicate glass, and is as safe as ever. Bakeware sold in Europe under the Pyrex name is still made (in France) of borosilicate glass, and so is also the same tough product that it always was. I did not find out anything about these products in Asia or Australia.
But, in the US, Pyrex glassware is now made of tempered soda-lime glass at a plant in Charleroi, Pennsylvania. Ordinary soda-lime glass is what windows, jars, and beer bottles are made of, and are extremely susceptible to thermal shock shattering, as people have known for centuries. The new US soda-lime Pyrex is "tempered", however.
Soda-lime glass can be "tempered" by either a thermal or a chemical process, which makes it stronger, but not all that much more resistant to thermal shock. Two layers of tempered soda-lime glass sandwiching a plastic film is auto window safety glass.
The instructions now provided with US soda-lime Pyrex cookware do caution the user to be more careful about fast temperature changes, but who actually reads such instructions? Point is, the American people are used to the more resistant borosilicate glass. The soda-lime variety is simply going to break more often in the kind of kitchen duty traditional from prior decades.
Why did they do this? Simply, to make more money, and because they could. Soda-lime glass is cheaper than borosilicate glass.
This is a classic case of plain-old bottom-dollar thinking without regard to any ethical or legal restraints. They covered their legal butts with the revised instructions that nobody reads.
There is nothing in the American marketplace about the tradename Pyrex to prevent them from substituting the more susceptible soda-lime glass and selling it for a borosilicate price, under a tradename that people think still stands for shock-resistant. A deception!
And that is precisely what they did here (although not in Europe, not yet, anyway).
Americans screwing other Americans for profit. Ain't deregulation and laissez-faire wonderful?