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Can That Go In The Microwave?

posted in Around the Kitchen by Lisa Freeman

The microwave is one of the most frequently used pieces of cooking equipment in the kitchen. It’s the fastest and simplest way to reheat something with minimal fuss. But be careful! It only takes one incident of something exploding or sparks flying around like a fireworks display to cause plenty of fear of your microwave.


Remember: A microwave cooks things at a very high temperature and very quickly, and not all food items and containers react well to that combination. You don’t want to risk damaging your microwave or getting hurt! So here’s a guide to what you should not put in your microwave:

  1. Aluminum Foil: Unless you’re trying to replicate some crazy science experiment in your microwave, or you’re ready to buy a new one, don’t put aluminum foil in there. The resulting display of crackling lightning will not be amusing. If you need to cover something to prevent the burp-n-splatter reaction that food often has in the microwave, use wax paper or even a simple paper towel.
    Any covering you use should be loosely laid over your bowl or plate. Plastic wrap can also be used safely, but it’s generally recommended that it does not directly touch your meat or other food items.
  2. Stainless Forks, Spoons & Knives: Again, no metal of any kind, please! I confess to having stirred some soup in a large bowl and inadvertently leaving the spoon in, only to witness a mini-lightning storm occurring in my angry microwave. If this happens to you, simply turn the thing off quickly, and DO NOT reach in to take the flatware out immediately! It can be very hot, so give things a few minutes to cool down.
  3. Family Heirloom China: Your grandma would not be happy to know that her treasured china is twirling around in your microwave. Many china patterns contain painted metal trim and designs, and these are a no-no in micros. Even if you don’t see a metal in the decoration, the painted pattern could be ruined since they are not generally designed for higher temps.
  4. Plastic or Paper Bags: Just because popcorn comes in a paper bag, doesn’t mean that you can just put an ordinary brown lunch bag in your microwave. The same goes for ordinary plastic bags such as those you get from the supermarket or wimpy sandwich bags with a Ziploc. There are specific brands made just for microwave cooking, so be sure to use those exclusively.
  5. Non-microwave Safe Dishware: If you turn over a cup, plate or bowl, you’ll see those all-important words: Microwave Safe. If your container does not say this, do not put it in the micro. Plastics in particular are subject to meltdown if they are not safe for such high temps. Margarine tubs, water bottles, mustard bottles and those take-home containers you get at restaurants or your favorite Chinese noodle shop are not microwave safe. So, unless you enjoy cleaning gooey Kung Pao Chicken from the crevices of your machine, don’t take the chance.
  6. Sponges: You may have heard the old rumor that putting a dirty sponge in a micro will rid it of all bacteria and clean it. People, this is total hogwash and can leave your beloved microwave with a terrible stinky sponge odor. Sponges, are very inexpensive to replace, or you can simply toss it in your dishwasher for a cleansing once a week. Why risk a burn mark on your microwave?
  7. Grapes & Fruits: You should not put any fruit in a microwave thinking that it’s a speedy way to dry it. This does not work and is quite dangerous. Grapes in particular have a habit of exploding. In fact, you should not put veggies in there without piercing holes in them first either, such as potatoes.
  8. Hard boiled eggs: Cooking eggs in the microwave is darned tricky, unless you’re doing something basic like scrambled eggs. That’s about all I ever recommend you try. No matter what, do not try to hard boil an egg in the machine! Heating anything in a tightly sealed container (which is basically what an egg in its shell is) means that you’ve got a mini bomb waiting to go off. You should not even re-heat an already hard boiled egg (without the shell) in the microwave, as there have been numerous cases of these exploding as well.
  9. Boiling Plain Water: You might think this is just plain silly, but boiling water in a microwave causes quite a few trips to the emergency room annually. You’ve got water that is super hot, while the glass container or cup it’s in generally remains cool. Then you go and dump a tea bag or spoonful of sugar into it, which is filled with lots of air bubbles. Boom! This can even happen if you stick a cold metal spoon into the water. The chances of this are even worse if you nuke your water a second time because you think your water is not hot enough. You’re way better off heating water on the stovetop or in your coffeemaker.

A microwave is not a toy. So be careful. If you’re not sure whether or not something can be put in the microwave, err on the side of caution and don’t do it. At least that way you eliminate all potential risk. As much as I enjoy fireworks and the occasional lightning storm, I don’t want to see them in your kitchen!

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7 Comments

Big John said:

You’re a bit wrong about boiling water. Temperature of an inserted object has nothing to do with it. If you just put water in a Pyrex and stick it in the microwave, that’s bad. There is no place on the sides or bottom for the water to nucleate on — you see this in a pot of water as little bubbles forming on the surface of the pot as it comes up in temperature. Drop something (non-metallic) in there that has a ‘rough’ surface (toothpick comes to mind) and you won’t have this exploding problem. The second you would touch the plain Pyrex boiled water, nucleation would take off and *pop* goes the water since it’s superboiled — over 212 degrees!

Crystal said:

If anyone is really curious as to what the light show looks like when you put something weird in the microwave – anything from an egg to a packet of soy sauce – do a You Tube search for “Is it Ok to Microwave This?” :P

Lisa Freeman said:

You are right, Crystal! Use the link under the aluminum foil paragraph and you can see a YouTube image in action wiht all the zapping happening. It’s crazy stuff!

Maya Cutie said:

Can you microwave paper bowls????

startcooking said:

Generally speaking it is fine to microwave paper plates so I’m sure you should not have a problem with microwaving paper bowls. Check with the manufacture to be sure!

aj said:

Have you tried to freshen your sponges in the microwave? I have put my sponges especially the newer organic ones in the microwave and I have to say they do come out without smell as if all the bacteria or whatever was causing the smell is gone. I like to clean them on a very regular basis (every other day), that could be very costly to me to change them as often as I like to clean them.

startcooking said:

Hi aj,

This can be tricky depending on what your sponges are made of.
Some sponges could end up igniting in the microwave!

I use a bamboo cleaning cloth which says to zap it for 4 minutes in the microwave to kill bacteria. I would NOT recommend doing this to an ordinary sponge.

K.