March 06, 2008

Things were different then

So one time us five kids were in the back of the station wagon driving home from up north and the other four start making up Mr. Wizard episodes. My brothers and sisters were having a gay old time talking about the new color and new musical chord Mr. Wizard had invented. I'm younger than they are and I hadn't seen the show; they told me about the 50s TV program Watch Mr. Wizard that taught science to kids. I still didn't think it was funny so I went back to staring out the window.

I was just thinking about Pyrex and read about an experiment Mr. Wizard had done where he put two glass bowls on a block of dry ice. Mr. Wizard pours molten lead into the bowls and the one that isn't made of Pyrex shatters. There is a burst of fog as the lead hits the dry ice.

This experiment wouldn't work today. Starting from when it was first produced by Corning in 1915, Pyrex was made from thermal-shock-resistant borosilicate glass. In 1998 Corning spun off World Kitchen which started making Pyrex from cheaper soda-lime glass and the packaging now states that the Pyrex kitchenware must never be used over a flame, on stove tops, under a broiler, or in a toaster oven. There are reports of the new Pyrex products shattering violently, producing large sharp cutting edges.

I love the classic Pyrex products we got as wedding gifts, like a baking dish and measuring pitchers. So versatile, so durable and now, so collectable.


At March 06, 2008 5:43 PM , Blogger rigtenzin said...

I have old pyrex, how do I know if it's the good stuff? Not by experimentation, I hope.

At March 06, 2008 9:50 PM , Blogger Matt_J said...

I was hoping there was an easy test, like a Bunsen flame test using a Bic lighter, or a test of the refreactive index, but there's not. In our kitchen some stuff says 'Oven Proof' and some says 'Not for lab or stovetop use', so maybe that will tell you.
(Note that Pyrex laboratory glassware IS still borosilicate.)
If it is the good stuff you should be able to give it a strong thermal shock with absolutely no problem. Like take it out of a 400 F oven with hot pad and drop it into a snowbank or sink full of cold water. Won't be a problem for true Pyrex.
Py from the Greek root for heat (pyrotechnics, pyromaniac), plus rex, Roman for king. Or, king of pies, as you like.

At March 14, 2008 3:30 PM , Blogger rigtenzin said...

The labels are the key. I just looked through the bunch and found a mixture. I remember pouring water into a pyrex pie pan, because some sweet potatoes had dried out in the oven. That was a mistake. The pyrex pie plate cracked immediately.


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