It’s a common part of the modern kitchen, but many people remain unsure about how to use their microwave safely. It may seem alarmingly technical, but once you understand the basic principles, you’ll be using this convenient bit of kitchen kit with ease.

How it works

While it may seem like magic, microwaves work by using radio waves at preset frequencies. These target the water molecules within your food, rather than providing the general heat you would expect from an oven. The waves make the water molecules vibrate, and it is this movement that generates the heat.

As you can see, this process is very different to boiling a kettle or putting a baking tray in a hot oven. Therefore, it stands to reason that there are some specific dos and don’ts when it comes to what you put in the microwave.


As you may remember from school science lessons, if you heat something that contains liquid and/or a gas, it will expand. However, if it has no room to expand, the pressure will build up, and can result in an explosion, particularly if it is heated very quickly. For this reason, you must never put a sealed container of any sort in your microwave.

This also applies to foods with skins and shells, such as potatoes or eggs. If you want to cook these things in your microwave, then you should carefully pierce it with a skewer in several places to ensure that the steam has an escape route. What’s more, if you’re a fan of ready meals, make sure to poke a few holes in any polythene coverings before hitting start.

However, a perforated covering is a great way to stop bubbling liquids splashing all over the inside of your microwave, so make sure to keep this in mind.


A good rule of thumb is to avoid putting metal objects in the microwave, unless you don’t mind buying a new microwave. This is because any metal that is not a flat plane can cause arcing, which is essentially a series of sparks. These can seriously damage your microwave, and also create dangerous levels of nitrous oxides and ozone.

Surprisingly, even some porcelains can contain thin metal films, so make sure to check whether your containers are microwave-safe (this should be written somewhere on the bottom of the item) before you get started.


Since microwaves heat food by way of the water molecules throughout the substance, it stands to reason that it’s impossible to get the lovely crispy tops that are commonplace in oven cooking. This means that if you want to get this effect for your pies, baked potatoes or other dishes, it’s best to use the traditional oven.

However, if you can’t bear to wait an hour or more for your baked potatoes, a good trick is to cook them until they’re almost done in the microwave, then pop them into the oven for five to ten minutes for those lovely crispy skins.

© Axonn 2015