Pyrex baking pan: not in toaster oven?
I was hoping to do some baking in my fairly large (.7 cu feet) toaster oven, but when I looked closely at the instructions for my new pyrex pie-pan it says not to use it in a toaster oven. Anyone use one in a toaster oven? Isn't 350 degrees in a toaster oven the same as in a regular oven, or does the proximity to the heating elements make a big difference to pyrex?
thanks for any info
Never use a glass baking dish in an oven with exposed radiant heat elements. If it's only air heating your glass dishes, you should be fine. But, when strong infrared is used (as in heating elements in many electric stoves which are exposed inside the oven) you stand a good chance of encountering problems. The reason is uneven heating, especially on the parts of the glass that aren't in contact with food. When the glass is hot, it expands and warps the piece. Depending on how sudden the change in temperature, the temperature of the air in the oven, the temperature of the food, etc., this can cause the glass to crack or shatter. Also, the glass, while in the hot oven, can deform more easily in response to those stresses. However, once the pan is pulled out of the oven, the parts not in contact with food (which were the hottest) are the fastest to cool, and cool the most, thus creating stresses from shrinking. However, since the glass piece is now cooler, it can't deform as easily as in a hot state, which leaves your cold glass dish in a 'stressed' state.
Anytime glass is stressed it usually won't break *unless* there's a small flaw or scratch in the glass. Then, the stress gets concentrated near the flaw, and if there's enough stress, the glass starts to break. Notice I said 'starts to break'. Since the initial break is itself also a flaw, it causes more breaks, which cause more flaws, which cause... well, you get the picture. Essentially, all the stress in the piece is relieved at once, with the net effect that the piece shatters itself, or 'explodes' into many small bits.
For an extreme example and some visuals of the phenomenon, do a search for "Prince Rupert's drops". There are a couple of good videos on youtube:
And this one on glass annealing:
Wow, I just had a look at this page:
I think I will be throwing away all of my pyrex pie pans. Too bad, they were cheap and worked well. I had no idea that explosion was a potential problem when using pyrex. Can anyone recommend and good, inexpensive deep dish pie pan?
i love my anchor hocking glass deep dish pie pan, however, the website has a warning that clearly states their glassware should not be used in a toaster oven.
but if you're looking for a good one to use in the oven, mine has served me very well...
It may depend on the toaster oven and operating mode. Smaller ovens, especially in toast or broil mode will produce a concentrated heat. A larger one set to bake at 350 would be much less of a problem. If the oven just uses a bottom element during bake, setting the glass pan on suitable metal sheet might also diffuse the heat.