Category: 

Is it Dangerous to Put Metal in a Microwave?

A microwave.
Certain types of metal can catch fire if heated in a microwave.
Metal in a microwave can overheat the magnetron.
Article Details
  • Written By: Brendan McGuigan
  • Edited By: Bronwyn Harris
  • Last Modified Date: 01 September 2014
  • Copyright Protected:
    2003-2014
    Conjecture Corporation
  • Print this Article
Free Widgets for your Site/Blog
Bill Clinton met John F. Kennedy when he was 16.  more...

September 2 ,  1666 :  The "Great Fire of London" burned down more than 13,000 buildings, including St. Paul's   more...

If properly handled, it is entirely safe to use metal in a microwave. The traditional wisdom stems from the fact that when improperly handled, metal can arc and cause problems. While it takes some care, and should certainly not just be attempted randomly, there is no reason why everyone shouldn’t be able to use metal in a microwave.

Microwave ovens work by using a device called a magnetron that sends out microwave radiation — electromagnetic waves — at a frequency of about 2.45 GHz, meaning they vibrate at almost two and a half billion times a second. When these waves come into contact with metal, they excite its electrons, which then start moving rapidly, and bounce the microwaves bounce off them. For this reason, we can say that metal reflects microwaves.

Many other substances, most notably water and fats, don’t reflect microwaves. Instead, they absorb the energy, which in turn heats up whatever absorbed it, and that’s how food gets cooked.

Ad

When one puts metal in a microwave, and that metal is long and pointed, it essentially acts as an antenna to the microwave energy bouncing off of it. This can create arcs of energy, which can cause sparks that tend to scare people. The sparks can also arc to the edge of the microwave if they’re near enough, and may even cause an increase in temperature within the magnetron, reducing the life of the microwave. Because of the danger to the life of the machine, and because of the fear such arcing causes in consumers, most manufacturers recommend that people not use metal in one.

These small arcs actually are almost never cause for alarm. A microwave is closed while operating, and a small arc of this magnitude is little different from a static discharge when your finger touches a piece of metal if you’ve been walking across carpet. Only certain metal in a microwave, most notably thin metal stripping that is often used as decoration on some china or glass, is cause for alarm. This metal can actually heat up enough to catch fire, or at least damage the item it’s on.

In fact, one of the biggest dangers people have when putting metal in a microwave is that they choose some sort of metal that has plastic attached. Many metal pots and pans have plastic handles made of phenolic, which may explode if placed in the microwave. There are, however, pots and pans made specifically for use in the microwave that are made of metal. These are usually labeled as Microwave Safe, and can be used for a wide range of cooking.

Although not for everyone, cooking with metal in a microwave can actually give results closer to traditional convection cooking than any other form of microwave cooking. If the proper materials are used, and care is taken, cooking with metal can produce brown crusts, and perfectly evenly heated foods.

Ad

More from Wisegeek

You might also Like

Discuss this Article

anon347923
Post 9

I microwaved my travel mug that has trace metal in it (a.k.a. the screws attaching the handle to the mug). It's radiating this weird smell. Is it still safe to use? I rather not get brain damage or whatever from using it.

anon345883
Post 8

I heat food in take out aluminum pans all the time with no problems.

anon321221
Post 7

I scrubbed the inside of my microwave and accidentally scraped some of the plastic coating off the bottom. Now the metal is showing through; about a 1/4 inch spot. Is it safe to use now?

anon192287
Post 5

My son put a jar of objects in the microwave and I started to hear a poppinmg sound after it was going for several seconds. I looked in and saw sparks flying! In the jar were several coins, paper clips and other metal objects as well as a small battery. At the longest I would say the micorwave was going for about 30 seconds.

I am wondering if the microwave is now damanged and if there potentially could have been any harmful exposure to me or my son from the metal and battery in the microwave. Thank you!

anon181115
Post 4

A good rule of thumb is to avoid putting thin metals into a microwave (forks, knives, spoons, aluminum foil, etc.) Thick metals or metal objects with no obvious thin edges are probably okay. I always use a microwave to reheat my coffee that is in a stainless steel travel mug that has plastic top and handle.

turquoise
Post 3

My roommate put a metal cookie sheet into the microwave and burned a hole into the back. The hole wasn't all the way through, but it wasn't very small either. Anyway, we had to pay for a new microwave. Our landlord was very upset and he wouldn't let us use it because he said it might start a fire. We bought a new microwave and a bunch of microwave safe containers after that but I still don't let my roommate near the microwave.

ysmina
Post 2

@burcidi-- You can use both metal and aluminum in the microwave, you just have to be careful with how you use it.

You can even buy microwaves with metal shelves now, so it's not true that it's unsafe. It's just that if there is a lot of metal or aluminum, the electromagnetic waves might bounce around too much, get really hot and damage the inside of the microwave. But a container with some metal lining or a little bit of aluminum foil will be just fine. In fact, if you take a look at your microwave manual, I'm sure they have some tips as to how you can use aluminum and metal.

I actually put aluminum in the microwave quite often, like when I have chicken drumsticks with the ends covered in aluminum. Using metal and aluminum can be a good idea, especially if you don't want part of the food to heat up as much. That part covered in metal or aluminum will reflect the waves, so it won't overheat or burn.

burcidi
Post 1

I am one of those people who cannot use metal in microwaves because it's too scary! I'm so surprised that those sparks are completely normal. I think I also reached the conclusion that metal is unsafe for the microwave because putting aluminum in the microwave also causes sparks and aluminum is not recommended for microwave use. They say that aluminum damages the oven because just like metal containers, they don't absorb the waves but reflect them. So what is the difference between use of metal in the microwave and use of aluminum? Aren't they essentially the same or similar?

Post your comments

Post Anonymously

Login

username
password
forgot password?

Register

username
password
confirm
email