Can You Microwave Aluminum Foil?

I remember when I was young enough to start “cooking” (which was pretty much only microwaving popcorn or something similar at that time) things myself my parents told me a few simple rules.

First, don’t put your hand on the stove. And second, don’t put any sort of metal in the microwave. I have to say, between you and me, that for the most part, I obeyed these rules. But, I still managed to burn my hands a couple of times, as well as see some sparks fly in the microwave. This latter was often because I was trying to reheat a cup of tea or a cup of coffee and the mug had a metal rim. If you’ve never done this, what you see is pretty much a super tiny sparkler firework going off in your microwave – while nice on the 4th of July, definitely not good to see in your microwave.

However, the blanket rule “don’t put any metal in the microwave” may not be as good of a rule as we think (except for kids, maybe) as there are some nuances that can allow for it.

So, can you microwave aluminum foil? Yes, it turns out you actually can put aluminum foil in the microwave! But there are some very important rules to keep in mind when doing so. 

Read on to learn more.

Why Might you Want to Microwave Aluminum Foil?

There are quite a few reasons that you may want to microwave aluminum foil, but a lot of it comes down to convenience. However, you can also use aluminum foil in a strategic way to prevent or promote the cooking of some types of food. This is actually already in place in a few items that you put into your microwave – popcorn and Hot Pockets. While there are probably others, these are some of the most common. 

When it comes to popcorn, have you ever wondered why it says that you should always put a certain side of the popcorn bag facing upwards? The reason for this is that the popcorn bag is lined with super-thin aluminum foil, which, when placed downwards, acts as a pan and is capable of raising the temperature much faster than heating up water just through the microwave.

For the inventor of microwave popcorn, Jim Watkins, it took a lot of research to determine exactly how much foil was required to act as an accelerator without causing the microwave oven to fail.

And in the Hot Pockets sleeve, there is a material referred to as a susceptor, which usually incorporates aluminum flakes as one of the primary materials to make it work.

However, for laymen and household cooks, convenience is the most likely reason for microwaving aluminum foil. This is because oftentimes when you have leftovers or takeout, it will come in an aluminum container. So, to save a bit of time and effort, it’s much easier to just pop the whole thing into the microwave, right?

Well, I have good news. Despite what we were told growing up, you can do just that, as long as you take some precautions. 

Can You Microwave Aluminum Foil?

Yup, you can certainly use aluminum foil in the microwave. This is very surprising to most people as many microwave manuals, as well as the overall public perception, demonstrate that it’s thought that it’s unsafe or that it will definitely damage the microwave.

But it’s been proven by a study that using aluminum foil in microwaves is fine. The USDA also states that using aluminum foil in the microwave in the proper way is also safe. 

The study debunks the myths and misinformation that have been spread pretty much since microwaves were invented. Some of these myths include that microwaving aluminum foil will break your microwave, or that microwaving food in an aluminum container can cause cancer or other health issues. In the aforementioned study, they tested this in a period of time that’s equivalent to 32 years of average household service life and found “no negative destructive influence on the magnetron operation”. (The magnetron is the mechanism that creates the microwaves that cook the food). 

Additionally, the study found that heating food in aluminum foil trays does not affect microwave safety when instructions are followed. In the case of arcing, no damage will be done to the oven wall, but it may cause minor cosmetic defects. So, in the worst case, and you do see some arcing (a few sparks), then the worst damage you might see is merely cosmetic. 

However, if precautions aren’t taken, then you can, in fact, damage your microwave or harm yourself. 

What Happens When you Microwave Aluminum Foil?

To understand what happens when you microwave aluminum foil, you first need to understand how microwaves work in general. Electron tubes called magnetrons create microwaves inside ovens, and the reflected microwaves are absorbed by the food that is inside. Microwaves cause the water molecules in food to vibrate, creating heat that cooks the food – this is why foods that are high in water, such as fresh vegetables, cook faster than other foods. 

There is a myth that food in the microwave cooks from the inside out, but this isn’t true. If you cook thick foods you will find the inside is still the last part to be cooked. 

So, what happens when you microwave aluminum foil? Well, aluminum, or other types of metal for that matter, will reflect these microwaves. While the outside of the microwave may be plastic oftentimes, the inside of the microwave is a big metal box, which contains the microwave radiation so it doesn’t escape. So metal being microwaved isn’t the problem. What causes the problem is if there is too much aluminum foil, it’s balled up, or it touches the wall. Any of these things can cause severe arcing that may damage your microwave because the aluminum can’t properly contain the energy from the microwaves. Additionally, if there is no place for the microwaves to go (like into the food to excite the water molecules), they will go back into the magnetron and can damage it. 

Can You Microwave Aluminum Foil Containers?

Yes, you can definitely microwave aluminum foil containers. Of all of the aluminum items, using an aluminum container is probably the most practical. This is because most likely it’s a takeaway food container and it’s super convenient to do. However, if you microwave an aluminum foil container, it’s important to follow some of the precautions I’ve already mentioned. But here are all of the precautions that you should take: 

  • Place trays in the center of the oven plate so that they don’t touch the walls.
  • Where possible, trays should have a depth of fewer than 1.5 inches.
  • Tray bottoms should be covered with food to the greatest extent possible.
  • Microwaves should be turned off immediately if arcing (electric sparks) occurs. While it will not damage the oven or start a fire, it may cause cosmetic damage to the microwave wall.
  • You should be careful when using a paper or cardboard lid on aluminum trays, as the heated aluminum could potentially set the paper/cardboard ablaze.
  • You should place a glass or ceramic plate under your aluminum tray if your microwave turntable is metal.
  • Aluminum shouldn’t be crumpled, it needs to be as flat as possible. 

Can You Microwave Aluminum Cookware?

While it’s technically safe to microwave aluminum cookware (assuming you followed the aforementioned rules) it’s something that you should avoid doing.

This is because it will simply do a bad job of reheating your food as most aluminum cookware is going to be deeper than 1.5 inches.

If it’s any deeper than that, the food will not cook evenly because the aluminum will block the microwaves that cook the food.

So, for the best results, avoid microwaving aluminum cookware and use a more tolerant microwave-safe dish or container. 

Alternatives to Microwaving Aluminum Foil

The alternatives to microwaving aluminum foil depend on what you plan on microwaving.

If it’s leftover food in an aluminum foil container, you can put it on any microwave-safe plate or container and then cover it with a microwave food cover, or even a paper towel to prevent splattering. If you are using aluminum foil to cover the food then, instead, you can use any number of items that are microwave-safe.

They include parchment paper, baking paper, a silicone lid, or even a silicone mat. However, the most convenient, easy to use, and my personal favorite, is parchment paper.