What does it mean for cookware to be microwave safe?

The global is full moon of unanswerable questions. Where resides the soul ? Can a person actually ever know another ? What is death like ? such mysteries abound. I have seen wonders in this global, dear Reader, but I confess that I was not prepare for this : It ’ s in truth, actually hard to get anyone to tell you what makes something “ microwave safe. ”

That ’ s not hyperbole. In the weeks I ’ ve been working on this fib, I ’ ve had multiple sources fall through, people and companies volition and tidal bore to participate until they see the interrogate, “ What makes something microwave safe ? ” then there ’ s a meep meep and a puff of fume, and they ’ re off. I got nothing beyond the obvious. ( The obvious : “ Microwave safe dishes are condom to use in the microwave. ” ) The U.S. Food & Drug Administration pointed me toward respective resources concerning microwaves. This one says, in short, that you should use “ glass, ceramic, and credit card containers labeled for microwave oven use, ” but that ’ s not an answer. ( It besides says to avoid “ super-heated water, ” which can explode out of the cup if you so much as be active it and nowadays I ’ ve got a new fear, thanks FDA. ) ad

This one has a bit more to offer :

Glass, newspaper, ceramic, or fictile containers are used in microwave cook because microwaves pass through these materials. Although such containers can not be heated by microwaves, they can become hot from the heating system of the food cook inside .

The U.S. Department Of Agriculture besides offers a brief guide, but besides nothing beyond what seems obvious : Avoid plastic containers unless it ’ randomness marked microwave-safe. Don ’ deoxythymidine monophosphate let fictile wrap touch your food. Don ’ metric ton microwave brown paper bags, grocery store credit card bags, or newspapers. still it begs the motion : What does it mean for cooking utensil to be microwave safe ? Is it merely about temperature—a bowl that you nuke and won ’ deoxythymidine monophosphate burn the bejesus out of you ? Or is it more a food safety issue, such as chemicals leaching out ? ad

enter Takeout “ Food Science ” subscriber David McCowan to the rescue. While he emphasized that he was answering my questions as a physicist, not a food scientist, he still had plenty to offer. The identify international relations and security network ’ t what makes microwaving food safe. It ’ randomness what makes it insecure. “ I don ’ metric ton know what the product engineer ’ s answer would be, but microwave-safe to me means that the material when used in the microwave will not break or deform, become excessively hot to handle, give off dangerous chemicals into the food or air, or lawsuit price to the microwave, ” he revealed via e-mail. ad

Things that are microwave-unsafe aren ’ deoxythymidine monophosphate limited to dishes and containers : Microwaves work by causing water system molecules in food to vibrate, and those molecules then jostle all the other molecules, creating heating system. But that means that anything in which water can be trapped could potentially explode, so don ’ metric ton microwave watermelons. besides “ sharp-edged metallic element objects ” ( i.e., forks, knives, and aluminum foil ) can make sparks fly. ( That ’ sulfur bad. ) ad

Because most containers aren ’ triiodothyronine watery, they aren ’ t heated directly by the microwave, he explains. It ’ s the food that heats the containers up. That ’ second true of formative, metallic element ( provided the surface is placid, big, and un-crumply ), paper… you get the mind. therefore why aren ’ t all non-crinkly-metal containers designated microwave-safe ? “ The lineage is a little less clear when a material will itself get warm or will warp in the microwave. Styrofoam, for exercise, does not get directly heated in the microwave ( since it contains no body of water ), but certain forms are soft enough that they can melt ( or at least deform ) from indirect heating as the hot food inside transfers its heat to the container. ” He besides mentions that some ceramics contain remainder water, meaning the cup of tea itself could heat up, creating a tan gamble.

( A site called Cooking For Engineers suggested that some glassware that international relations and security network ’ t microwave-safe may have to do with micro bubbles that are portray in the glass, which can expand during the microwave process and… kaboom. ) McCowan outlined several of the ways something could be “ microwave-unsafe, ” ( let ’ s call it M.U.S., for giggles ) though this should not be considered an exhaustive list ( see : super-heated freakin ’ water. ) ad

  • If the material could leach stuff into the food, like melamine
  • Metal in general is a bad idea, so watch out for decorative metal bands in teacups and other things. While in theory, a very smooth metal bowl “with no sharp lip” would be safe, “the line between smooth and pointy is continuous… most metal containers fall ambiguously in the middle.” M.U.S.
  • If the material could heat up itself, like the aforementioned ceramics or something covered in a paint or glaze that heats up, that’s bad M.U.S. news.
  • The M.U.S. material could bubble, melt, or become otherwise deformed, when heated indirectly by the food.


That means we have an answer to the question. Something is microwave safe if it :

  1. Won’t heat up directly because there’s no water in it
  2. Won’t melt when the food heats it indirectly
  3. Won’t vomit chemicals into your food when it’s heated
  4. Doesn’t contain metal that’s even moderately sharp-edged.

McCowan charitable leaves me, and thus us, with suggestions : “ Avoid anything with cosmetic metallic element foils or flakes in the paint unless the manufacturer says it is safe, ” and assume most ceramics are safe. ( not to scare you more, but some ceramic mugs are insecure even if it says “ microwave-safe. ” According to Sub-Zero and Wolf appliances, some paints on mugs attract microwaves and can make the countenance perilously hot. ) ad

For cookwares that aren ’ metric ton marked, there ’ s a test from the web site of GE Appliances to see if a particular utensil or dish is microwave-safe : Fill a cup with water, and seat it alongside the cooking utensil in motion inside a microwave. Heat for a minute on senior high school. If the water gets hot and the cooking utensil stays cool, it ’ s dependable to use. If the cooking utensil gets hot, good, don ’ deoxythymidine monophosphate put it in the microwave again. alternatively, McCowan suggests you can besides fill the container in question with water system and placing it in the microwave for 30 seconds. That ’ s not enough clock for the water system to heat up the dish, so if the serve is warm, that ’ s a bad bless. “ If it ’ randomness still cool after a full minute of warming, then it ’ s credibly okay. ” Just don ’ thymine heat it besides a lot, because super-charged water is terrifying .