Why You Should Stop Baking with Your Chipped Pyrex

December 24, 2016

Earlier this month, Sheree noticed a small chip on the edge of her Pyrex pie plate* and turned to the Hotline to find out if it was still safe to bake with.

Drbabs advised against it, pointing her to a recap of some of Pyrex’s Safety and Usage Instructions, one of which notes: “DO NOT use or repair any item that is chipped, cracked or scratched.” (Chips can turn into cracks, and cracks combined with a temperature change—like putting a glass dish in an oven or freezer—compromise the structural integrity of the whole item.)

Not chipped, and not Pyrex, but you get the idea. Photo by James Ransom

A reminder to take the time to read equipment instructions isn’t the only smart tip we picked up from drbabs on the Hotline lately—which is why she's this month’s Hotline MVP.

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Here are couple more of our favorite tips from her:

I haven't made these (But I want to! Thanks!). Here is my suggestion: Make the cookie dough today, refrigerate it for the 3 hours, then bake off 3 to 4 cookies, let them cool thoroughly, wrap them well, and freeze them overnight. See what happens when you take them out tomorrow. (Let them defrost uncovered so you don't get condensation on them.) I suspect they will be fine, but if not, you can freeze the unbaked dough for another time and make something else.

With candy you are always going by temperature. (Your pot could be broader and shallower than hers [which would affect the time].) Make sure the liquid is heating evenly and you are not just finding a hot spot with your thermometer.

Congratulations to drbabs and thanks to everyone who participates over on the Hotline—the community wouldn’t be the same without you.

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Top Comment:
“I still have a scar on my leg from a pyrex bowl shattering after my mother put simmering hot sauerkraut into a room temperature bowl. Perhaps today's Pyrex is doesn't shatter unless it's at 450 degrees, but for those of us who have vintage bowls, I'd strongly recommend a bit more caution. ”
— Diane T.

New here? To thank our members for their dedication to helping out their fellow cooks, every month we’ll choose a Food52er whose activity on the Hotline has caught our eye, and treat him or her to a $25 gift certificate to our Shop. Want to boost your kitchen karma? We’re looking for enthusiastic participation throughout the month that is helpful, thoughtful, and considerate.

*(If you have vague recollections of Internet stories of exploding Pyrex dishes, World Kitchen would like you to know that their Pyrex glass products “are, and always have been, durable, reliable and safe.” Fact-checking sites like Snopes note that some viral claims are false, like: "The Consumer Product Safety Commission (CPSC) has determined that Pyrex glass bakeware products are unsafe." (CPSC has never issued a recall or reported a safety issue with Pyrex.) Though they've found other pieces are true, saying: "Pyrex, like all brands of glass bakeware, is subject to breakage due to thermal shock" and, "Different brands of glass bakeware have different usage guidelines, and what consumers consider "ordinary use" may not fall within those guidelines."

See what other Food52 readers are saying.

  • Diane T
    Diane T
  • mikedalena
  • drbabs
  • Daisy Palacios
    Daisy Palacios
  • Nancy
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Diane T. February 14, 2017
My memory about Pyrex exploding isn't vague and doesn't come from some internet story. I still have a scar on my leg from a pyrex bowl shattering after my mother put simmering hot sauerkraut into a room temperature bowl. Perhaps today's Pyrex is doesn't shatter unless it's at 450 degrees, but for those of us who have vintage bowls, I'd strongly recommend a bit more caution.
mikedalena February 14, 2017
Quartz inversion is a constant in the universe. It's the laws of physics. Glass one billion years ago is glass last week. It's likely that was very hot product. In fact, your experience reinforces my statement. A cold bowl being exposed to thermal shock, the rapid change in temperature, is exactly what causes glass to shatter. Your anecdote is valid but serves to support the immutable laws of physics.
mikedalena December 26, 2016
Thermal shock, the condition that causes glass to break from a rapid temperature change occurs at 450 degrees Fahrenheit. At 450 the electrons in the molecules of glass (quartz) jump from their A orbits to their B orbits due to the additional energy they are exposed to. This is called quartz inversion. If this jump in orbits, either when heating up to above 450 or cooling down from above 450, occurs too rapidly/all at once the material will crack. The drop or jump in orbit literally tears the glass apart. One doesn't really need to worry about putting a Pyrex dish into a 450 oven because the rise in temperature isn't that rapid when one places a Pyrex dish on the oven's rack. However, a precipitous drop in temperature from above 450 will definitely cause the dish to crack.

Basically, don't stress about your dishes if you're cooking well below the 450 mark and only be concerned when you're above that mark if you take the cooking container from a 450+ oven. In those instances don't set the dish on a cold tile surface or directly into the freezer. Place the hot out of the 500 degree oven dish on a wood cutting board or a rack of some sort to prevent thermal shock.

I'm not afraid of glass Pyrex dishes or ceramics with chips in them due to the immutable laws of physics (love science!) but I would throw out anything that is cracked. It's structure is weakened and it is a disaster waiting to happen.
Daisy P. April 22, 2020
This is really good information Mike thanks! I was just stressing because I Recently bought a vintage pyrex with a chip on it. I didnt buy it just to display it. So I can use it in an oven that is below 450 degrees?
drbabs December 25, 2016
Wow! Thanks, Food52!
Nancy December 27, 2016
Congrats! Always value your comments...
drbabs December 27, 2016
Thank you!