Some Questions About Pyrex

[Kikujiro]

You can't use Pyrex on the stovetop, right? So: if someone's boiling water on a gas hob, in a translucent pot or casserole so you can see inside, and this is taking place fifteen years ago, what if anything could the pot be made from?

thanks

Edited March 25, 2003 by Kikujiro (log)

[Jason Perlow]

Pyrex. You can use it on a gas stove. Not many people doing it nowadays though, but in the 70's it was vogue to have Pyrex cookware.

[bigbear]

I think that Pyrex Visionware has been around for 20 years or so.

[Stone]

I saw Alton Brown reduce some jus in a Pyrex baking dish (the rib roast episode). But the dish itself (or the two I have) specifically say not to use on a stove top. And a friend of mine freaked when I did.

[Jason Perlow]

Specifically, we are talking about Pyrex Flameware:

http://www.acorpe.com/id173.htm

http://www.leaves-flowers.com/pyrex/py-010.html

[g.johnson]

There's nothing very remarkable about glass that's able to withstand a naked flame. Think chemistry class.

Edit: That said, the thickness required for a saucepan will cause problems since a temperature gradient across a thick piece of glass will lead to uneven expansion and stress that could shatter the pot. My guess is that pyrex is designed to expand very little with heating to reduce that stress. It'll still shatter if you place a hot dish in cold water, though.

Edited March 25, 2003 by g.johnson (log)

[Kikujiro]

Aha! Thank you. I thought Pyrex, but the no stovetop thing threw me.

Edited March 25, 2003 by Kikujiro (log)

[Jason Perlow]

I think that Pyrex Visionware has been around for 20 years or so.

http://search.ebay.com/search/search.dll?c...pyrex+flameware

According to some of the items in this ebay category, back to the 1940's.

[bigbear]

Visionware also.

[Suzanne F]

You can't use Pyrex on the stovetop, right? So: if someone's boiling water on a gas hob, in a translucent pot or casserole so you can see inside, and this is taking place fifteen years ago, what if anything could the pot be made from?

thanks

There was no pot. It was a special type of water that holds its shape when boiled. It was an experiment that failed, alas, because no one could figure out how to cut off a chunk to make only one cup of tea.

[fimbul]

There was no pot. It was a special type of water that holds its shape when boiled. It was an experiment that failed, alas, because no one could figure out how to cut off a chunk to make only one cup of tea.

And the coffee goes all over the keyboard.

Thank you, I needed that.

[Sandra Levine]

That said, the thickness required for a saucepan will cause problems since a temperature gradient across a thick piece of glass

It wasn't good for direct cooking, but it made a great double boiler, because you could actually see the water in the lower pot and adjust the flame accordingly.

[memesuze]

My mother always made her coffee in a Pyrex percolator directly on the flame on her Chambers range.

memesuze

[richw]

I carelessly placed a pryex roasting pan on a coil burner to deglaze and it blew up like a BOMB. There wasn't a piece of the thing left larger than a dime. Luckily nobody was hurt but I sure wanted to eat that chicken!

[=Mark]

As I recall the Pyrex cookware hyped in the 70s and 80s had major problems with food sticking. Also, glass is exceptionally poor as a conductor of heat. It looked cool but ultimately lost out due to poor performance.

[Wimpy]

How about Corningware? Can it be used on top of a gas burner?

[jhlurie]

I've still got one tucked away somewhere. Its good for boiling water, and maybe pasta or rice. Fun for the whole family.

[rozrapp]

How about Corningware?  Can it be used on top of a gas burner?

Yes.

Re: pyrex pots. In the late 1960's, I purchased a pyrex double boiler for use on a gas cooktop. While the larger, bottom pot broke a long time ago -- not while in use though -- I still have the smaller top pot and cover and do use them occasionally.

Btw, people who keep kosher find pyrex pots extremely useful because they can be used to cook both dairy and meat (though not together, or course). Any item made from glass -- including dishes, glasses, etc. -- is considered pareve. Pots like stainless steel, copper, etc., can only be used for either dairy or meat.

[Suzanne F]

Oh, I LOVED my Pyrex double-boilers! The only d-b in which you can always see the water level.

I've gone through at least 2. Once the top pot went when I cooked oatmeal in it directly over the flame, and then thought I could just put it over the boiling water in the bottom to keep warm. Wrong. All the other tops and bottoms broke from getting smacked too hard against things like the floor.

fimbul -- you're very welcome. It's been a rough few days here, too.

[Wholemeal Crank]

On KCRW's Good Food podcast for 8/22/09, a guest was discussing pies with the Evan Kleinman, and mentioned an episode of 'exploding pie' because her pyrex pie plate 'lost its temper' and exploded. She said pyrex expires!

I've never heard of this phenomenon. Anyone know what she is referring to?

[Chris Amirault]

Interesting! Over on the USG's "Ask a Scientist" website, we have this exchange:

Would you please tell me why a Pyrex casserole that I have used for years would explode when I took it out of the oven. It was hot but I placed it on the top of the stove to cool. It exploded into very small shards of glass.

* * * * *

Several things may have happened.

1. One tip-off is your comment "I have used for years...". Glass (Pyrex) and others can develop invisible (except using a pair of polarizing filters) stresses that finally cause the bowl to crack. Once a crack starts to propagate it can shatter into small shards.

2. If you had scratched or chipped the bowl ( and it could have been small enough that you might not even be aware of it) this too sets up stress sites that allow (1.) to occur more readily.

That doesn't sound like milk going bad; that sounds like materials science: little stress points build without your awareness and the whole sheebang loses integrity.

Has this happened to anyone? And why is poor Pyrex being blamed? Does it happen with Corningware too?

Edited September 16, 2009 by Chris Amirault
clarify quotation (log)

[Kouign Aman]

This answers part of the Q on another discussion about why glass refrigerator dishes went out of style!

[HungryC]

Never had a Pyrex dish shatter--borosilicate glass is way harder to scratch than plain ol' glass. I have seen the nasty results of Corningware's delamination---a bazillion needle-sharp shards. I used a Corningware bowl to feed my outdoor cat, and his enthusiastic eating moved the bowl quite a bit on the rough, concrete patio. One day, I dumped in the kibble, and kapow--it just shredded. Scared the hell out of me & kitty. He wouldn't eat out of a bowl at all for a few days!

[lemniscate]

If you do a google search of "pyrex explodes" or "pyrex exploding" there's lots of hits. A theory is that the newer Pyrex is not made out of borosilicate glass anymore. I have had a newer Pyrex rectangular dish crack in half in the oven (it was a very new dish) but not reduced into shards. The old 60's/70's pyrex and fire king I inherited have never chipped, cracked or shattered in almost daily use. Just my gut, but I don't trust the new glassware now. I have never heard of expiring glassware before.

[baroness]

Glass is one of my passions and a favorite creative medium. I may know more about glass than food!

Glass cannot expire or 'lose its temper'.

There are things that can stress the glass, thus opening the door to problems:

IN MAKING THE ITEM

Incompatible glasses mixed in the making of the item

Bad technique when joining parts

Improper annealing during the making of the item

ITEM IN USE

Sudden, dramatic changes in temperature (freezer to oven or broiler; oven or stovetop to a cooler surface, particularly if it is wet as well)

Surface scratching (if you have ever cut glass, this is obvious!)

Borosilicate glass is more resistant to breakage than softer glass. I have heard that at least some Pyrex is now foreign-made. Some of the Asian boro that is used for ART GLASS is pretty bad quality (and cheaper, of course) than American boro.

Some of my newer (foreign-made) Corningware prohibits stovetop use, a change from the American products.

I do not fear baking in glass, but do treat it with reasonable care.