Cooking For Engineers

[DougLassiter]

I'm getting a Corning stoneware 4qt casserole for a friend. I am very surprised by the caution not to use stoneware on the cooktop. I've been doing so with my Corning 4qt stoneware casserole for 40 years (as well as using it routinely in the oven). Soups, stews, pot roasts. You name it. So, um, what's the deal? I can understand that if you let the pot dry out, temperatures can get very high. But as long as there is water in it, things should be OK, right? Is there any issue about gas versus electric cooktop? I use electric

[Dilbert]

many ceramics do not manage stresses from wide temperature differences well - the uneven expansion causes them to crack / break / shatter.

works in the oven room temp to oven temps because air heats then up slowly - but under a broiler they'll likely break. some companies recommend not going from freezer to oven - too much thermal stress... many variations on the theme from 'just don't do it' to the old Corning borosilicate (very low expansion factor) Pyrex stuff. the new stuff is no longer borosilicate glass -

I'd say you've been lucky on your electric coils - starting with a cold coil and heating slowly obviously doesn't impose the same thermal shock/stress as for example a gas cooktop or plunking it on a already heated electric coil.

[DougLassiter]

Well, no question about rapid expansions and contractions. I understand completely that stovetop can inflict stresses that you don't get in the oven. BUT, I have to believe that if the pot has plenty of liquid (water) in it, the temperature change can't be that large that fast, and will never really exceed 100C.

I would like to believe that the correct rule should be, don't use it dry on the stovetop.

Freezer to oven would be an obvious no-no, because frozen water can't conduct heat away from the surface as fast as liquid can.

[DougLassiter]

It seems that the stovetop-capable material that Corning makes is called Pyroceram. That's different than the regular "stoneware". It is *possible* that the casserole dish I have is, in fact, that stuff. I have heard that there is some dishonesty on the market about labeling things Pyroceram that really aren't. As a result, getting it direct from Corning is probably the best bet.

[Dilbert]

stoneware is not Pyroceram . . .

[DougLassiter]

[quote="Dilbert"]stoneware is not Pyroceram . . .[/quote]

Which is exactly what I said.