Aluminium (British English) or aluminum (North America) foil (also known as tin foil, which is a misnomer) is a pliable type of cooking foil that you can readily bend or wrap around objects or dishes like metallic paper.
It’s made of the element aluminum and it’s prepared in thin metal leaves. The thickness of the foil is no more than 7.9 mils or 0.2 millimeters. You can avail of thinner aluminum foil gauges if you wish, like those measuring 0.24 mils or 6 micrometers.
So can you microwave aluminum foil? If not, then why not? If it’s absolutely not possible then why does microwaveable hot pockets have containers lined with aluminum?
Can You Microwave Aluminum Foil?
Many kids back in the day loved eating non-frosted pop tarts. Many children have woken up in the morning, open up a pack of pop tarts, then place the whole thing inside the microwave to heat up their deliciousness to the right degree.
However, the next thing they knew, there came sparks shooting inside the microwave like it was the 4th of July in there. What happened? As a child of yesteryear, you’ve probably been warned by your upset mother to never place pop tarts or anything with aluminum foil packaging inside the microwave.
Therefore, in regards to whether you should put aluminum foil in the microwave, the answer is a yes and a no. Yes, you can place it inside the microwave to the point of heating up your food safely. No, because putting foil in the microwave the wrong way can cause arcs or sparks, smoke, and fire.
What’s So Dangerous About Microwaving Foil?
The better question is “When is it okay to put foil in the microwave?” The answer is when you keep the sharp edges of the aluminum foil away from the microwave walls like with aluminum-lined hot pockets packaging then you can prevent fire, smoke, and sparks from happening.
Not only is tin foil a thin piece or sheet of metal that gets extremely hot as the microwaves pass through them and into the food itself. The bouncing microwave or micro radiowave radiation bounces around the metal box itself.
Additionally, the foil is too thin to reflect microwaves the same way the metal walls of the microwave interior could. Sparks typically fly when “arcing” occurs, such that metal-to-metal contact of the foil to the walls results in the development of electricity or sparks.
What Exactly Happens If You Put Aluminum Foil in the Microwave?
The higher the wattage number of your microwave, the likelier for your aluminum foil to create sparks regardless of its edge sharpness or the amount of foil present.
Microwave wattage refers to the amount of energy flowing in a given direction. There’s more energy being created by a 1-kilowatt microwave compared to a 700-watt microwave for sure. As the energy interacts with water molecules and turn to heat, the foil also gets hot.
Every element has a melting point. Aluminum specifically melts at 1,221°F. If your microwave is at 1.5 kilowatts, this converts to around 1,112°F or 572°C.
A microwave can reach beyond-boiling-point superheated temperatures easily. Once the aluminum melts or gets into contact with microwave walls, the sparks will definitely fly.
Sharp Edges versus Smooth Edges
Another variable that affects your chances of creating sparks and electrical arcing is the sharpness of the foil.
Aluminum foil that’s been crumpled in a way that it has sharp edges is likelier to cause fireworks inside your microwave oven versus aluminum foil that lines your plate in a way where its edges are smooth or round.
The problem with tin foil is that they crumple like paper to the touch, thus creating those dangerous sharp edges. This is another reason why the aluminum-lined hot pocket container is safer to heat up in your microwave compared to a wad of aluminum foil covering the fried fish you wish to reheat.
How Comes Aluminum Foil Works Fine with Conventional Ovens?
Aluminum foil works fine with conventional ovens because it’s dealing with heat conduction alone instead of water molecule excitation care of microwave radiation. The aluminum foil gets hot in both scenarios, but with microwaves it actually gets superheated.
The sparks also fly with the foil’s interaction with the walls, which could lead to the food burning due to all the sparks happening, if not the machine overheating altogether. The way the foil interacts with the oven depends on the amount of foil, microwave wattage, or if arcing even occurs.
It’s a crapshoot of what will happen. In the case of foil-lined hot pockets, the amount of foil is limited to the packaging and you can prevent putting the foil too close to the walls. Therefore, sparks won’t fly as much compared to the foil packaging of pop tarts.
How Come Sometimes Arcing or Sparks Don’t Occur?
The more foil is involved the likelier the dangerous things that typically happen when you put metal inside your microwave will happen, only this time the microwaves don’t bounce back as much with your foil compared to silverware due to how thin the foil is.
What this means is that when certain variables aren’t met that can impact your risk for “arcing” or electrical sparks like you put fireworks inside your microwave, then it’s possible to put aluminum in your microwave and not have anything dangerous happen.
However, like in the case of shaking a soda can, even though there’s a possibility that the soda won’t explode on your face, you don’t want to risk opening it. It’s like playing Russian roulette with your microwave. The only way to win is to not play in the first place.
Therefore, just because you used aluminum foil once and didn’t end up with a busted microwave, it doesn’t mean that there’s no risk.
Aluminum foil can be used for microwaving if you’re able to minimize arcing risk. the foil used in the packaging of hot pockets, for example, is made in such a way that there’s little chance for the foil to get into contact with the metal walls of your microwave, thus resulting in sparks or a fire hazard.
As long as you can limit the distance between the tin foil and the metal walls of your microwave interior, then you can use it the same way you’d use it for heating up food items on a conventional oven.
- “Can you put Aluminum Foil in a Microwave?“, SmallApplincePlanet.com, Retrieved April 21, 2021
- “Facts about aluminium foil“, AluFoil.org, Retrieved May 27, 2020.