Stainless steel cookware is the staple of every kitchen, whether home or professional kitchen. It’s non-reactive, has good heat retention, and can be used for basically every cooking technique imaginable, from sautéing and braising to searing and simmering.
But despite all of its many great qualities, there is one question that always seems to come up: “can you put stainless steel in the microwave?”
Can You Microwave Stainless Steel?
As a general rule, it’s not safe to put any metal in the microwave, including stainless steel. This is because, during the microwaving process, all metals counteract the microwave’s radiation. This causes the metal to create sparks as it heats, potentially damaging your microwave or even starting a fire.
The FDA itself reiterates that metal cookware should not be used directly in microwaves for the reasons mentioned above (1). Let me explain why in more detail.
Here’s Why You Can’t Microwave Metal
As you may already know, microwaves use radiation to heat food. These waves permeate the food and cause the molecules inside it to vibrate; specifically, they interact with water, fat, and sugar molecules.
Thus, these vibrations of the molecules that actually heat the food and not some kind of electrical charge floating around inside the microwave, as many people may believe.
With microwave-safe containers such as glasses or ceramics, the microwaves are able to pass right through them because they don’t interact with them. Metal, on the other hand, reflects the microwaves, disrupting them and preventing them from heating anything.
This is not the problem by itself. Flat, thick pieces of metal won’t likely form an electric arc that causes a sparking effect. The worst thing that will happen if you cover a dish with a flat piece of metal is that the food simply won’t heat up.
This is also the reason why manufacturers use metal to construct the walls of microwaves: to confine the microwaves inside.
What can become a problem is when you have a metal crinkled or formed into a complex shape such as forks or knives. When these objects with sharp edges are microwaved, they reflect the microwaves back and forth, bouncing around inside the microwave between the microwaved metal object and the interior metal walls of the microwave.
This causes the intensity of the radiation to increase exponentially, becoming powerful enough to cause an electric arc that eventually leads to sparking.
What About Stainless Steel?
Stainless steel is basically just regular steel doped with chromium to make it resistant to corrosion. But other than that, it isn’t much different from regular steel.
Thus, when it comes to microwaving, these behaviors will apply to both regular steel and stainless steel: the reflection and redirection of the microwaves by metal objects. This means that you can’t put either type in a microwave without causing damage.
A flat sheet of stainless steel sitting on a microwave won’t likely cause any damage, but a stainless steel fork will definitely pop some sparks.
What a Microwave-Safe Container Should Be
A microwave-safe container is one that does not interact with the microwaves, just like glass or ceramics. It must be constructed of materials that do not warp when exposed to heat and won’t leach chemicals into the food when heated.
What Other Things Should You Never Put in the Microwave?
Now you know that microwaving stainless steel is a big no-no. But what about other materials? Here are some things that you may assume can go into the microwave but really should not.
1. Chinese Take-Out Containers:
What most people don’t realize is that Chinese take-out containers have a hard-to-remove metal handle that is a surefire recipe for disaster. You’ll be surprised to know how many people have had to deal with the spark or even fire that this container has caused every year.
2. Lunch Bags
While a lunch bag might seem harmless, it actually one of the things that the USDA warns not to put in the microwave. Here’s what the USDA says about it: “They are not sanitary, may cause a fire, and may emit toxic fumes.”
3. Yogurt Containers
There’s a reason why yogurt containers are categorized as one-time-use containers. They are meant to be thrown out after a single use and are not designed to withstand the heat of the microwave. Inside microwaves, they could warp or melt, which could lead to a release of chemicals and toxic fumes.
4. Styrofoam Containers
We have heard that Styrofoam should not go into the microwave for safety reasons as it’s just another type of plastic. But just in case you have never heard this warning, I wanted to include it here.
5. Travel Mugs
Most travel mugs are made out of stainless steel, so it goes without saying that they aren’t meant for microwaves unless they are labeled microwave-safe. Be sure to check the bottom of the mug to see if it says “microwave safe” before putting it in the microwave.
6. Tupperware Containers
Most Tupperware containers are made from plastics, and we have already gone over the dangers of microwaving plastics. However, there are some plastic storage containers that are designed for microwaves. Just be sure to double-check the label before you microwave.
7. Aluminum Foil
Any kind of metal, even something as thin as the foil that’s covering your food, can cause sparks in the microwave. So it goes without saying that you should not put aluminum foil in the microwave.
If you’re unsure of whether or not a stainless is safe to put in the microwave, the best advice is to just avoid microwaving it altogether. It’s better to err on the side of caution rather than having to find out the hard way that the fork you thought was safe can actually cause a fire.
Besides, it doesn’t take much to transfer your leftovers to microwave-safe containers like glass or ceramic.