Can You Microwave Coffee in a Styrofoam Cup?

by Charlie
Styrofoam cup of coffee

The microwave is great for reheating almost anything, but what about your take-out coffee in a Styrofoam cup that went cold sitting on your desk? Can you just pop it in the microwave to reheat it? Is this safe and how long should you microwave coffee in a Styrofoam cup for?

Can you microwave coffee in a Styrofoam cup? Yes, you can microwave coffee in a Styrofoam cup if it is labeled microwave-safe. It is recommended to microwave your coffee in a Styrofoam cup on medium and you should heat your coffee at this temperature for no more than 30 seconds.

We take you through all there is to know about the type of foam cup you need, how long to heat it for, and at what temperature.

Is it OK to Microwave Coffee in a Styrofoam Cup?

First and foremost, you must check to see if your Styrofoam cup is ok to use in the microwave. You can do this by looking for the microwave-safe symbol on the base of the cup. This is usually a few horizontal squiggly lines or even a picture of a microwave with squiggly lines inside it. It is usually embossed on foam cups and doesn’t have any color so you may not see it at first glance.

This is really important because if your Styrofoam cup isn’t microwave safe, it can cause all manner of health and safety issues to you AND your microwave. So do make sure you see this logo before even thinking about using it in the microwave.

When it comes to flavor, reheating your coffee in the microwave will leave it tasting less than its best and lacking that lovely fresh taste and smell, but when needs must, it’s OK and better than the coffee going to waste.

It wouldn’t be recommended to actually make your coffee in a Styrofoam cup in the microwave because it would mean having to heat it for too long, and this would increase the risk of health and safety issues. A quick reheat is fine as long as the correct type of Styrofoam cup is used at the correct temperature, and for the recommended time.

Is it Safe to Microwave Coffee in a Styrofoam Cup?

According to FDA approved standards, if your Styrofoam cup is labeled microwave-safe then it is safe to use it in the microwave as long as you stick to the heating guidelines as detailed below. Ignoring the recommended heating temperature and time can not only result in nasty burns but also possible chemical toxicity. So to avoid either of these things from happening, it is essential to check your cup carefully before putting it in the microwave.

To keep it safe, when heating your coffee in a microwave in the correct type of Styrofoam cup, you must only use the advised heat setting and time. If you ignore either of these it could cause the contents to become harmful and it’s just not worth the risk, especially when plastics and polymers are known to contain carcinogenic properties.

How Long to Microwave Coffee in a Styrofoam Cup?

The actual recommended heat setting to use on your microwave oven is medium and you should heat your coffee at this temperature for no more than 30 seconds. If you put the microwave on full power or exceed the recommended 30 seconds, this would result in the Styrofoam cup degrading and becoming harmful to the contents, and ultimately to you!

As much as these cups have been deemed safe and have a microwave-safe symbol on them, they really are not the best thing to use in a microwave for the above reasons.

What are Styrofoam Cups Made From?

Styrofoam is a tradename and a more recent type of polystyrene. Polystyrene was invented in 1839 and was soon realized to have extremely useful applications due to it being so lightweight, buoyant, and water-resistant. It was used in the manufacture of boats and docks and was also noted for its great insulation properties. This led to it being used in many buildings to keep them warm.

Styrofoam came along a little later in the 1940’s and was made even more lightweight as it contains 98% air! The term Styrofoam is used generically for all types of polystyrene, but the true Styrofoam is actually blue in color and is made from “extruded” polystyrene foam (XPF) and not “expanded” polystyrene foam (EPF).

Confusing right? Well, we do love using brand names generically – it’s the same as calling all tissues “Kleenex”! So polystyrene eventually evolved into having a whole range of uses. One of these was the humble coffee cup and that’s because it is so good at keeping the heat in and cold out.

But despite its virtues, polystyrene and therefore Styrofoam DO contain plastic and other harmful chemicals. These are not only harmful to the environment, but also to you if not used correctly. So sticking to the guidelines is your best bet if you want to look after your health.

Tips for Microwaving Coffee in a Styrofoam Cup

Ultimately, polystyrene cups were invented to have the contents poured into them, not for them to be heated up. Even though the more advanced and supposedly safe equivalent is approved for microwave use, it still has its risks.

Here are some tips to keep you safe when microwaving your coffee in a Styrofoam cup:

  • Never reuse a Styrofoam container for a second time in the microwave. This is because during the first time around the heating process could have caused damage to the fabric of the container which is not always obvious to the eye. This could result in harmful chemicals leeching into your coffee that would not be good for your health.
  • If you see any damage to your Styrofoam cup such as dents, blisters, or rips do not use it in the microwave at all. Transfer the contents to a ceramic or glass container and reheat in that. It will not only be safer from a burns point of view, but also ceramic or glass will not be harmful to the contents or you.
  • Always be careful if adding sugar to microwaved coffee as it can cause it to bubble up and spill over, which could result in nasty burns.

Final Thoughts

Styrofoam was, and indeed still is a great invention in lots of ways. However, things have moved on since the 1940s. We now realize how damaging all plastics are to the environment, especially single-use ones such as Styrofoam cups. In fact, many places such as Seattle and San Francisco in the USA, as well as other major cities around the world are now banning them.

This is because of the harm they do to the environment and the amount of time they take to break down. Also, when Styrofoam or polystyrene food and drink containers are discarded, animals can get hold of them and ingest the plastic.

So as much as it can be handy to grab a coffee in a Styrofoam cup, consider the impact of this on the environment and maybe get yourself a reusable coffee mug which you can get filled at your favorite coffee shop and use time and time again. There are some really cool designs out there that will not only be better for your personal health, but also for the health of the planet.

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