Can you heat paper cups in the microwave? - It is safe?

At some point, you’ve probably experienced the waste of a perfectly good coffee mug because you forgot it on the kitchen counter and it got cold.

At that point, people are often faced with the question of whether or not they should pop their paper cup filled with coffee into the microwave to reheat it.

This brings us to the key question:

Can paper cups be heated in the microwave?

No, it is not recommended to microwave paper cups. The microwave process causes the paper to break down and release potentially harmful chemicals into your food or even catch fire. The paper cup will also be deformed and damaged.

With that being said, keep reading because we’re going to dig into the reasons why you shouldn’t microwave paper cups. We will also present some suggestions and alternatives that you can explore when faced with this dilemma.

Understanding how microwaves work

Before we delve into the question of paper cups and whether or not they are safe to microwave, we should first look at how this heating method works.

Microwave technology has been around for a long time and has become an everyday convenience that we all enjoy. However, for our purposes, we must lift the veil in order to respond effectively to the issue at hand.

Microwave ovens work differently than traditional ovens that use direct exposure to heat to heat or cook food.

These appliances work by emitting microwave particles that penetrate the food and agitate the molecules, causing friction, which causes heat, which is distributed by convection.

Be aware, however, that a microwave oven has the notorious problem of not being able to heat things evenly.

At the same time, the heating process used by microwaves can have an adverse impact on the material being heated. Make sure you remember this part as it will play a big role later on.

What are paper cups made of?

If you’ve ever had your morning cup of coffee to go, you’ve probably come across these paper cups. They are everywhere, and most fast food restaurants and coffee shops use this container to serve their coffee.

However, contrary to what you might expect, paper is not the only material used to make these cups. If you look closely, you will no doubt notice that there is a thin layer of film on the inside of the cup.

This may not surprise you, but this layer on the inside of the cup is usually made of wax. However, there are cases when it is plastic.

The purpose of this film is quite simple: it’s there to prevent your drink from leaking onto the paper itself. We’re sure we don’t need to tell you that without this movie, that glass would be a soggy pile of mush instantly.

Even microwaving organic products can sometimes be a risk, such as wooden bowls, which can burn or catch fire.

What happens when you put paper cups in the microwave?

Simply put, two issues arise if you decide to microwave any paper products, including paper plates. First of all, there is a risk that the paper will be irreparably deformed and damaged.

Second, the glues, waxes, plastics, and other materials used to maintain the structural integrity of the glass will most likely begin to melt and flake off during the heating process. This can also release harmful chemicals into your drink or food.

Needless to say, both problems stem from the fact that your mug’s liner is not microwaveable. It simply will not be able to withstand the high temperatures of the microwave.

In the end, both your drink and your cup will be spoiled.

In fact, more than just your mug can end up damaged. Most paper cups are made with a polyethylene inner liner. This type of plastic poses serious health risks in the microwave.

Potential risks and dangers

While we’ve discussed what will happen to your mug once you’ve microwaved it, you should also understand that there are additional risks and dangers involved.

We have listed the risks below: 

• A big mess – This is a big inconvenience to be prepared to deal with should you decide to go ahead with microwaving your paper cup. Once it starts to warp and become unstable, you can only hope that your drink will start to spill all over the inside of your microwave.
• Ruining your drink - In the unlikely event that your glass is not completely destroyed by microwave exposure, you will find that your reheated drink will be tasteless. Remember when we said that the glue and liner on your paper cup is likely to start to melt? Well, chances are that particles of those materials will start to seep into your drink when that happens. Needless to say, this will be an undeniably unpleasant and unhealthy experience.
• Long-term health problems - It must be said here that you will have a bigger problem if you decide to consume the contents of the microwaveable paper cups for a long period. This is because the chemicals in glue, plastic, and wax have been shown to have detrimental effects on your health. Specifically, certain plastics release estrogen-like chemicals into food, stimulating excessive estrogen production. This is especially dangerous among women, as it can affect the function of the reproductive organs. Furthermore, it can also increase the chances of obesity and other chronic health problems.
• Fire Hazard - It should come as no surprise that microwaved paper cups pose a major fire hazard. After all, the materials used to make these glasses are naturally flammable. So if left exposed to the high heat levels of the microwave for too long, your paper cup can easily start to smoke and catch fire. If you’re not careful, this situation can quickly get out of hand.

These are just some of the dangers and risks involved in microwaving paper cups. They range from an especially bad cup of coffee to your house burning down and you developing serious health complications yourself.

So, if we had to give advice: don’t do it.

The supposed comfort it provides is not worth the dangers it entails. This is especially true due to the fact that there are alternative solutions to your problem that require very little effort.

Alternatives to paper cups

It shouldn’t surprise you that there are endless alternative solutions to the problem at hand.

While you shouldn’t heat the paper cup directly in the microwave, there’s nothing stopping you from transferring its contents to a microwave-safe container and heating it up.

How do you know if something is microwave safe?

This is the first question you should ask yourself. After all, the last thing you want to do is transfer your drink to another mug that isn’t microwave-safe either. That would just be a waste of effort and you would end up trading one problem set for another.

That being said, you have to look for the microwave compatibility label on the base of the mug. This will tell you everything you need to know. The importance of this cannot be overstated, so you should always make sure you do it before you microwave anything.

Microwave Safe Options

Before anything else, it’s worth reiterating that you should check the label on the specific mug you’re going to heat in your microwave.

After all, not all products are created equal. Therefore, the fact that they use the same material does not necessarily mean that they are all safe to use in the microwave.

Here are two types of glasses you can use that are likely to be microwave safe:

• Heat Proof Glassware – There are specific types of glassware made from borosilicate and soda lime that are known to work well in the microwave. They are specifically designed to withstand heat and have no problem with rapid changes in temperature.
• Ceramic - Most ceramic mugs are perfectly safe to use in the microwave. So you shouldn’t hesitate to microwave it, if you see that your drink is getting colder than its optimal conditions.

There you have it: our complete guide to why you shouldn’t microwave your paper cups.

The fact is that they are not made for that kind of heating process. So, as expected, the glasses will start to break as soon as you put them in there. Luckily, there are alternative options at your disposal.