Your microwave serves as a multipurpose device capable of heating up your coffee, reheating your leftovers, popping your popcorn, and defrosting frozen food. It’s likely you’re using it more than ever before because of the worldwide pandemic-induced lockdown orders and most Americans staying home in order to avoid getting infected by the coronavirus.
However, here’s something you absolutely must not do. You should never put metal in your microwave. So what happens when you put metal in a microwave? Mostly bad and dangerous things.
What Happens When You Put Metal in a Microwave?
Arcing happens. What is arcing? Arcing is when metal things like silverware or metal foil from packaging are exposed to micro radiowaves or electromagnetic waves from the magnetron of your microwave unit. It produces sparks and electricity conducted by the metal.
Why is Arcing Bad for Microwaves?
You don’t want arcing to happen because the electricity and sparks could cause a fire on the dish you’re trying to cook or reheat. It happens whenever the metal makes contact with the metal oven walls.
Aside from burning the food, a short circuit could happen that damages the integrity of your microwave unit.
You may also like: What Are The Things You Should Never Put In The Microwave?
What Sort of Metal is Microwave-Banned?
It’s imperative that you don’t put anything metallic or anything made of steel inside this appliance. Even if it’s aluminum foil, it can get dangerous. If the recipe calls for aluminum foil inside the microwave, follow its instructions to ensure that the placement of the foil is safely done.
This includes foil on paper plates, stapes on packaging, or metal handles on containers.
The Real Dangers of Microwaving Metal
Any reflective or metallic metal reflects or deflects the microwave or radiowave rays, leading to all sorts of unintended consequences like sparks, electrical arcs, and internal damage.
The microwave interior is lined with metal on the inside to ensure the microwaves don’t bounce all over the circuitry. Metal to metal contact could create a spark, bolts, or fire that damages your dish or your microwave. It could overheat the food as well.
Will Your Microwave Explode If You Put Metal Inside of It?
No. It could get damaged but not explode. Movies like “American Hustle” tend to exaggerate the dangers of microwaving silverware or stainless steel utensils. The scene is both beneficial and detrimental in educating the public about the dangers of microwaving anything metal.
People might think the dangers of microwaving metal are overblown when they accidentally do it and nothing happens.
Is It a Hoax?
No, it’s not a hoax. Yes, even if a hot pocket has a metal lining in its packaging, it won’t necessarily result in your microwave exploding or something. However, that doesn’t debunk the concept of avoiding putting metal things inside your microwave because it’s dangerous.
To “safely” microwave metal or steel that you can’t remove from the dish (like a hot pocket), keep it more than 2.5 centimeters or an inch away from the metal walls of the oven.
What Happens When Metal Utensils Make Contact with the Microwave’s Metal Walls?
Arcing could happen if silverware utensils, steel anything, metal anything, or even aluminum foil is nearer than 2.5 centimeters or an inch away from the microwave oven’s metal walls.
Sparks and electricity could occur, the waves could bounce off so much on your food it catches fire or becomes charcoal, or the wayward electricity could damage the walls and penetrate the interior circuitry of your device.
Why Is It Sometimes Harmless?
Forgetting to remove a spoon or fork from your meal or beverage can sometimes be harmless because you’ve dodged a bullet. They’re not placed less than an inch or 2.5 centimeters away from the walls, which could cause arcing.
The food didn’t suffer too much microwave deflection and bombardment from the presence of the metal. Or the sparks didn’t cause harm on the dish or microwave. But you’re still playing Russian roulette by microwaving anything metal in the first place.
How Do Microwaves Work with Metals Anyway?
The microwave heats up things from the inside out by water molecule excitation through radiowave bombardment. So that’s how your microwave cooks dinner. However, what about metals? How does microwave radiation react to metals?
Absorbent and Deflective
Metals on the microscopic or atomic level are made up of lattice arrangements of atoms. The electrons freely flow between these arrangements.
The micro radiowaves will attract all the electrons on metals as they bounce inside your microwave oven the same way they do with the metal walls of your microwave. The electrons are then pulled back and forth, thus generating heat inside the metal that could superheat it.
The Thinner the Metal The Faster It Heats Up
The very real danger of leaving silverware inside a microwave is that their thinner material (like in the case of a big piece of aluminum foil or a cheap metal spoon and fork combo) can heat up extremely rapidly.
Anything superheated can cause havoc on your dish, your drink, or even the interior of the microwave itself. You could seriously damage your microwave with a superheated piece of metal for sure, especially when it’s compounded with arcing.
The Dangers of the Arcing Phenomenon
Your magnetron’s electromagnetic waves can also cause arcing to happen when it hits your metal something and it’s near the metal walls that are supposed to contain those microwaves in the first place.
Arcing is also a fire hazard since it produces electrical flashes and sparks that could ignite your food or further superheat your microwave metal with radiowave bombardment.
Many Possibilities of Failure
When you microwave a piece of metal and it causes arcing while being superheated, the microwave walls or the device itself could overheat as well. This is part of the reason why you shouldn’t heat up unopened canned goods.
The other reason is the building pressure of a superheated can of tuna can make it explode like a bomb. Take out the food from out of the can and heat it with a microwaveable plate to maximize safety.
What’s the History of Microwaves?
Percy Spencer discovered the principles of microwaves and helped develop the first microwave oven with the assistance of Raytheon, the company he was employed with.
Percy Spencer Invented Microwave Ovens
Percy Spencer, a Raytheon engineer, accidentally discovered the concept of microwaves shortly after the Second World War. To be more specific, an active radar’s radio waves ended up melting a “Mr. Goodbar” chocolate inside his pocket.
He then confirmed that microwaves caused the melting by popping popcorn and making an egg explode with them in front of a scientist.
Patenting the Technology
The technology was then patented by Raytheon before the company built the first microwave ovens. They looked like conventional ovens but those rotary dials instead controlled the time and the power level of the magnetron being used in order to shoot radiowaves unto food for quick heating.
At the time, they were all so huge and expensive that they only got used on military ships since they needed military-grade budgets to get bought.
The Technology Soon Became Available to Consumers
By the 1970s, the technology had become cheap and small enough to become available to the ordinary man instead of just the government or millionaires.
They soon had kitchen-top or countertop models available for general consumption in that time, including the push-button and digital ones that remain the de facto design of modern microwave ovens nowadays.
How Do Microwaves Work Anyway?
A microwave works by using its magnetron to produce micro or mini versions of radiowaves that excite the water molecules of any food or beverage you put inside it.
This leads to faster cooking and heating times at the expense of potentially drying out the dish or drink if overdone. Inside the device is the magnetron. This is the part of the microwave oven that produces microwaves, electromagnetic waves, or radio waves.
Further reading: What Can You Put in a Microwave?
More About the Magnetron
When your microwave oven is turned on, it’s the magnetron that releases electrons from a cathode, which is a negatively charged rod. The electrons travel into a chamber full of magnetic and electric fields.
They deflect the electrons in such a way that forces them to move around in a sweeping, circular motion. During this negative electronic motion, they brush up on the walls of the microwave chamber that have a positive charge to them.
These walls have cavities where the electrons zip and impart electricity, which makes them resonate as a specific frequency that produces electromagnetic or radio waves.
To Sum It Up
The microwave oven has metal walls on its insides that bounce back the microwaves or radiowaves directed at the main box. These bouncing miniature waves are what excite water molecules and heats up food and beverages so ridiculously fast.
The problem with microwaving metal is that the microwaves are bounced or deflected in ways unintended by the design of the oven. The metal can make the microwave less effective by absorbing the radiowaves, thus shielding the food from bombardment. It can also make the waves bounce off more, thus causing excessive bombardment. If it’s too close to the metal walls, arcing, electricity, and sparks could form.
- Adam Mann, “What’s Up With That: Metal in the Microwave Explodes—Or Does It?“, Wired.com, May 20, 2014
- Spoon U, “What Happens When You Put Metal in the Microwave“, Teen Vogue, August 5, 2017
- Melanie Pinola, “What Should and Shouldn’t I Microwave?“, Lifehacker.com, October 9, 2019
- “What Happens When You Put Metal In A Microwave?“, IFL Science, Retrieved March 10, 2021