Can You Put Tin Foil In The Microwave {Explained}

A microwave is a very handy gadget indeed. You can reheat food, cook entire meals, vegetables, nuke your cup of tea – the list goes on! Most of the time, you can whack a bowl full of covered leftovers in the microwave without a second thought. But, can you put tin foil in the microwave?

If you’ve ever done it, you will already know the answer! But for those that are wondering, let’s have a more detailed look into the answer to this question.

Is Aluminium Foil Safe To Put In The Microwave?

Is Aluminium Foil Safe To Put In The Microwave
  • Aluminium foil is made of metal, therefore it is a very good conductor of heat. Because a microwave heats things up very quickly, tin foil can be a fire hazard if you heat it in the microwave.
  • Microwaves work by generating radio waves, that spin water molecules in food – the friction of this then heats up the food.
  • Metal is reflective, so metal will reflect these radio waves, and they will bounce off the metal walls of the microwave.
  • You may find that if you put food covered with foil in the microwave, the food will not heat up – this happens when the metal foil reflects the radio waves.

There is, however, another possibility, which is far more dangerous and less of an irritation than an actual hazard!

  • The metal of the foil is so thin that they waves will not be reflected, but the metal will heat up so rapidly that it may actually set on fire.
  • Microwaves also use an electric field, which can cause a charge to run through metal. This can be very hazardous, not just for your food!
  • Anything that is heated up to very high temperatures very quickly can cause a fire hazard; tin foil in the microwave is no exception.
  • It does often happen that, even if you do put aluminium foil in the microwave, absolutely nothing happens.
  • Generally, a thick layer of aluminium foil will not set fire to your microwave, but it will cause issues with heating up your food.
  • If you are using small pieces of foil, or if they are crunched up, you are far more likely to encounter problems.

Putting aluminium foil in the microwave is not ALWAYS a recipe for certain disaster – but it is best avoided intentionally!

What Happens To Aluminium Foil In The Microwave?

Aluminium foil is a very, very thin piece of metal. Most metal cant be folded up and scrunched, can it? Aluminium foil, despite it being very thin and easy to fold around things, is actually made of metal!

Metal in large, thick sheets, can withstand the microwaves that heat up our food. Thin sheets of metal are more susceptible to being heated, however.

When microwaves hit sheets of tin foil, they heat them up very quickly. This in itself can cause problems – you can easily burn yourself on a sheet of hot metal.

The other problem is the scrunched, folded up edges of the tin foil. These sharp edges can also conduct an electrical current.

When sharp edges come into contact with heat and an electrical current, they can cause sparks. Sparks are not what you want inside your microwave!

If a spark jumps onto a piece of wax paper, or a particularly flammable bit of food, it can cause a potential fire in your microwave.

The two potential outcomes of foil in your microwave are:

  • Nothing much happens. There is no kitchen fire, but also your food does not heat up effectively because the metal reflects the radio waves.
  • The metal heats up to such a degree that it catches fire, or spreads sparks around the microwave and potentially causes a kitchen fire.

Here is a sightly dramatic video that shows what can happen – and why – when you put tin foil in the microwave:

What Happens If You Put Foil In The Microwave?

If you accidentally put a bit of foil in the microwave, don’t panic too much. All being well, the worst that will happen is the part of your food that is covered won’t heat up.

Flat pieces of aluminium foil may send out a little spark or two, but probably won’t do enough to damage your food or your microwave.

Scrunched up aluminium foil will cause more problems; it may generate enough sparks to burn the foil, but again, shouldn’t set fire to your microwave.

Cooking tin foil at high temperatures for a long time can cause damage to your microwave – the walls might get scorched, or worse, the microwave might catch fire.

Interestingly, you can happily place food that is held in aluminium trays directly into the microwave with no problem.

Aluminium trays are increasingly used to hold food, as they are a more sustainable option than plastic, and better at storing food than cardboard.

You may notice that food cooked in the microwave in these trays take a little longer to heat through, but you won’t notice any big sparks or explosions!

The problem generally comes with a really thin piece of aluminium foil, rather than a thick tray of aluminium.

Try to avoid putting foil in the microwave, but don’t panic overly about aluminium in the microwave in general.

Final Words

So, now you know. You CAN put tin foil in the microwave, and there’s no need to panic if you accidentally do so – but it is best avoided.

Forgetting that your leftovers are covered in foil before you nuke then is unlikely to burn your house down – but you shouldn’t make a habit of putting tin foil in the microwave.

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