Can You Microwave Foil? (Or KABOOOM?!?)

Can you microwave foil? Will my microwave explode? Will it taint my food? All good questions that don't have obvious answers.

Here's the thing...

Microwaves make life so much easier and seem so safe that we might sometimes think ANYTHING can go in there and it'll be fine.

But you do have to be mindful about what you put in your microwave because the last thing you want is plastic melted and burned into your food or an explosion in your kitchen, right?

So before you chuck your foil covered food in, close the door, and set that timer be sure to read this post right to the end to be on the safe side...

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Microwaving Food with Foil

Before you do anything, check your microwave user manual and heed manufacturer recommendations about what to not put in your microwave, heed this advice carefully to avoid culinary disasters. 

It is good to remember that it is usually fairly safe to put a small, uncrumpled piece of foil in your microwave when cooking your food, but there are terms and conditions of this which we will get into later. 

Microwaves, which heat your food, cannot pass through metals but are absorbed by food.

This is the basic reason as to why any food totally wrapped in foil or covered by a metal pan or dish, should not be put in the microwave, as the food will be unable to absorb any of these microwaves and produce any heat.

Another thing to be wary of. Do not operate your microwave oven when it is empty of food is tightly wrapped in aluminum foil, as it will cause damage to your microwave and the food simply will not heat up. 

Using a small piece of aluminum foil that is uncrumpled is okay though,  you can use it to cover areas of food, such as meat or poultry to prevent overcooking.

Some food may even come packaged in foil, if so check that it is safe to microwaves as it is, view the food-prep and cooking instructions and manufacturer recommendations before putting it in the microwave. 

It is also best to microwave food that are no more than 2” deep, do this to ensure that the food at the bottom is adequately cooked.

The last thing you want is food cooked at the top and cold at the bottom.

Using the microwave with foil


How does a Microwave work and why do you hear horror stories?

Microwaves are a great invention of the 20th and 21st century, they are not available in almost every single home, office, and kitchen all over the world.

And pretty much every microwave owner has also been avidly told at least once, not to put metal, and specifically not foil into the microwave, and if you haven’t been told, you have likely heard a horror story about it or seen an online video of someone managing to blow theirs up by doing so. 

You have probably by now heard at least once, a story about fires or explosions as a result of someone putting aluminum foil into a microwave.

Most people will tell you not to put foil in the microwave, but very few people actually know exactly why and what happens inside that little miracle cooking machine that makes this happen.

Microwave technology is very simple, microwaves are named so as they use microwaves to heat and cook food- fairly self-explanatory right?

Microwaves are a type of radio waves, in the case of most microwaves, their frequencies are around 2,500 megahertz.

With this range of frequency; waters, fats, and sugars will absorb them and heat up, as when they absorb the microwaves they are transferred into heat, and therefore, water boils and food cooks. 

However most plastics and ceramics will not absorb these microwaves, and so, are fine and this is a useful feature of a majority of culinary and serving items, such as plates and bowls.

But, what about metal?

What will happen if I Microwave foil?

The walls inside a microwave oven are actually made from metal, a thick metal and they actually act a bit like a mirror, rather than seeing your reflection and doing your hair in them, they reflect microwaves.

If you were to put your food in a pan made from heavy metal, then due to the material of the pan the food would not cook.

The pan would shield your food and your food would be not better coming out than going in. But there would be no fire or explosion.

However, when it comes to thin and sharp metals, like foil, things are different.

The electricity in the microwaves causes electric currents that will flow through the metal, in heavy metals and thick metals, like with pans or pots, there is no danger as they can tolerate the electricity.

But, aluminum foil is not quite so resilient and will find these electric currents overwhelming.

And so, it will heat up very quickly, so quickly in fact it will catch fire, think of it like friction, the more speed added to friction the more likely you are to catch a spark, like rubbing to sticks together. It is similar to foil in a microwave. 

It is even worse if the foil is crinkled, crunched, and has sharp or pointed edges.

As sharp edges cause sparks, this is due to an electron charge building and when the charge becomes strong enough it ionizes the air and creates a conductive path to the walls of the microwave.

But these sparks hitting the walls of the microwave is not the biggest concern, if the sparks were to hit anything like wax paper, or something flammable or already very hot, you are looking at a fairly substantial blaze and a need for a lot of water and probably a fire extinguisher. 

It is probably best to stick to non-meta solutions, there are many things available out there, of course, you can use some types of heat resistant plastics for some quick-cooking foods, dinner plates are also a good choice.

Some companies even make microwave intended food covers for occasions where you may need to reheat a meal. 

Maybe it’s best to keep the foil and the microwave apart for now.