Can You Microwave Cardboard Food and Takeout Containers?

Sometimes, it’s easier to reheat takeout in the container it came in. Our lives are busy, and we might need to leave our home soon or might not want to make more dishes we’ll need to set aside time to wash. But, is it a good idea to microwave cardboard food and takeout containers?

You can microwave cardboard food and takeout containers. However, you need to watch out for wax or plastic coatings, metal staples or clips, and plastic films or handles. You should also remove your container from any paper bags.

In this article, I’ll explain why microwaving cardboard food and takeout containers is mostly safe. I’ll also go over what they’re made of, what you should avoid microwaving, and how microwaves cook and reheat food.

Is Microwaving Cardboard Food and Takeout Containers Safe?

It can be challenging to know whether it is a good idea to microwave takeout in the container it came in. Are there certain containers you shouldn’t microwave? Are there things you should remove from your takeout containers beforehand?

Microwaving cardboard food and takeout containers is safe. While there are some containers you shouldn’t microwave, like those with wax or plastic coatings, they’re rare. Metal staples and plastic films, on the other hand, are easily removed.

Some people might worry that microwaving these containers isn’t safe. However, preparation can go a long way toward addressing that concern. If you remove any potentially unsafe parts or materials beforehand, then microwaving cardboard food and takeout containers should be perfectly safe.

Container Parts You Should Avoid Microwaving

So, what parts of your containers should you avoid microwaving? What is alright to leave behind? Are there certain types of containers you shouldn’t microwave at all?

When microwaving cardboard food and takeout containers, you should avoid containers that contain any of the following components:

  • Wax or plastic coatings
  • Metal staples or clips
  • Plastic clips, films, or handles
  • Brown paper bags

In the following sections, I will explain why you should avoid microwaving these materials.

Wax or Plastic Coatings

Wax coatings are used to keep moisture from getting in or out of the container. They also protect food from gases from other food in your fridge that hastens food spoilage. Most of today’s containers don’t have wax coatings. Instead, they have a polyethylene—or plastic—coating.

Whether it’s wax or plastic, microwaving creates fumes that aren’t healthy to breathe in or consume through your food. So, you should transfer food from coated containers to a plate or bowl instead of microwaving them in the original container.

You can also learn more about plastic coatings on food containers in this article by RecycleSpot.

Metal Staples or Clips

Metal staples or clips are sometimes used to hold containers together or keep them closed. However, even the smallest bit of metal, such as a staple, can create sparks when microwaved, causing fires or damaging the inside of your microwave.

Plastic Clips, Films, or Handles

As I said in the above section about wax and plastic coatings, plastic creates fumes that can damage your health when microwaved. This is also true for plastic clips, films, and handles. 

Even if you hold your breath when you open your microwave, they deposit themselves on your food and therefore get into your body when you eat it. So, it’s safest to avoid microwaving plastic in general.

Brown Paper Bags

While it may seem convenient to microwave your food inside the brown paper bag it came in, this is a fire hazard. Any sparks from metal can set the bag alight. If your paper is slightly damp, it’ll heat up alongside your food, which can also cause a fire.

What Are Cardboard Food and Takeout Containers Made Of?

If you’re worried about the safety of microwaving cardboard food and takeout containers, you may also be wondering what cardboard containers are made of.

Cardboard food and takeout containers are made from wood pulp prepared with sodium hydroxide, which is then pressed into paper and glued together. At the very least, you can expect your cardboard food and takeout containers to contain paper and glue.

However, there’s no need to worry about ingesting glue from your takeout containers. It’s inside the cardboard, holding it together, and likely won’t come in contact with your food.

What Are Recycled Cardboard Food and Takeout Containers Made Of?

This may leave you wondering: what about recycled cardboard?

Recycled cardboard food and takeout containers are made from the same materials as fresh ones. However, part of the pulp mixture used is new in order to prevent the poor quality that results from using recycled cardboard.

Containers made entirely from recycled cardboard with no new materials are soft and easy to tear. They also have a dull appearance that some consumers find displeasing. This is why recycled cardboard only contains some recycled material instead of being made entirely of it.

How Microwaves Heat Cook and Reheat Food

Microwaves use electromagnetic radiation to heat food up. The radiation process creates an important byproduct: thermal energy. In less scientific terms, microwaves heat the water content in your food, which then cooks or reheats it.
If you’re interested in seeing this mechanism in action, Scientific American has posted an experiment you can do at home.