Can You Put A Metal Coffee Cup In The Microwave? Is It Safe?

on September 16, 2022

If you own a metal coffee cup or even a travel mug that is made out of metal you may be wondering whether it is safe to put it into the microwave Is it safe or will it damage the microwave or will it catch fire?

The use of a microwave to heat food in metal objects is actually safe to do despite the myths that it will damage your microwave. However, you still need to take care with handling these objects as they can heat up extremely quickly and can potentially cause burns so always treat anything coming out of the microwave with respect.

There has been a Myth for an extended period of time that any metal in a microwave will cause major problems and even an explosion, however, this information is largely unfounded though there are a few caveats around it which need to be considered.

The first thing that many people don’t realize is that microwaves themselves are made of metal. this metal helps to contain the microwave released into the food to ensure that it does not affect the user. In the front of the microwave where there is a grill that allows light through so you can see your food cooking but the grill is made of metal and designed to keep the microwaves in the device.

So metals alone generally will not create an explosion however there are certain circumstances in which sparks can be generated from certain types of metals in certain configurations. So if you want to know more check out the video below in which a couple of people conducted a series of experiments that will demonstrate what happens when metal is put is a microwave.

In What Circumstances Could A Fire Be Created In A Microwave?

As mentioned earlier in the article metals are not that dangerous in the microwave, however, it is absolutely possible to create a fire if the right conditions are generated. In the video above sparks for generated when a large piece of foil was placed in the microwave and crumpled up

When heated for an extended period of time it was observed that sparks would jump from one section to another of the foil. However, the introduction of the foil alone would not be enough to cause a problem for microwaves because it does not spontaneously combust but the sparks that are being generated could be used to ignite a substance that was potentially flammable such as oil or fat.

To create these conditions the foil would need to be crumpled up specifically to allow the sparks to jump from one point to another which is not something that is normally done if you were using the microwave in a sensible fashion to heat food as people normally would. So a fire remains very unlikely and less the microwave is misused.

How Does A Microwave Actually Heat Food?

If you haven’t got a science background you may be wondering how microwaves even heat food in the first place because unlike other conventional cooking appliances you cannot feel any significant heat from anything other than the material that is in the microwave, so how does it actually heat the food?

The microwave as the name suggests uses microwaves or radio waves to heat food. Radio waves are part of the electromagnetic spectrum that includes light and a range of other waves such as ultraviolet infrared and even x-rays to name a few.

These radio waves are magnetic which means that they have the capacity to vibrate molecules within the food, particularly water because it has positively and negatively charged ends of the molecule. This means that each time a magnetic field is applied to a water molecule that is moving that it causes the water molecule to also move.

The kinetic energy (movement energy) is what we perceive as heat so when the waves are applied repeatedly to a substance with water in it, in particular, the water molecules begin to vibrate very rapidly which creates heat making the microwaves an extremely effective way to heat up food.

However, you may also notice that all microwaves have a rotating plate in them. The reason for the rotating plate is that when the microwaves are generated from the device bounce around inside the microwaves’ box and are not evenly distributed.

So to increase the chances that the food is heated evenly it is rotated on a glass plate which will typically ensure that the heat within the food is distributed more evenly. However, you will know from your experience that it will still get hot and cold spots within the food. This means that you do need to be careful because you can have areas within the food that are dangerously hot.

Is It Actually Possible To Burn Foods In A Microwave?

If you have ever used a microwave you may have experienced the situation where you have put the microwave on for a little bit too long and you get an extremely hot and overcooked piece of food, however, normally this will mean that the food has dried out or something like that rather than burnt so is it possible to actually burn food in a microwave?

The answer to this is yes it is absolutely possible to burn food in a microwave, however, you do need to take the cooking to an absolute extreme to get burnt food. I have first-hand experience of this as my oldest daughter decided one day to heat up a party pie in the microwave and put it on for 10 minutes.

After those 10 minutes, the party pies were black and burnt to the point where the char marks on the plate that the party pies were sitting on that could not be removed from the plate. So it is absolutely possible to burn food in a microwave, however, you normally need to create a circumstance where the time that the food spends in the microwave is somewhere in the order of 5 to 10 times longer than typically should.

Feature Article: “Sabotage #6: Loading metal into the microwave” by DocChewbacca is licensed under CC BY-NC-SA 2.0.