Do you have cold coffee leftover in a to-go cup in the morning because you got busy and didn’t get a chance to drink it?
If so, you might wonder if it’s safe to put your to-go cup in the microwave and reheat the contents so you can enjoy it hot. After all, if you had wanted cold coffee, you could have made or ordered cold coffee, and no one likes to waste it.
Can you microwave coffee cups?
The short answer is that you most likely shouldn’t microwave paper coffee cups because there are certain materials found in the cup’s makeup that can be problematic for you. You can reheat your coffee in a microwave-safe cup instead without a problem.
If you’re curious as to why microwaving a flimsy coffee cup isn’t ideal, we’re going to break this down for you. We’ll cover what these cups are made of, different types of cups, safety warnings, and much more for you below.
What do Manufacturers Make Coffee Cups Out of?
When you get a coffee if a to-go cup, you typically end up with a plastic lid on a disposable paper cup. However, paper isn’t the only material in this disposable cup.
If you take a look at the inside of the cup, you’ll notice that it has a thin film that makes it semi-shiny.
This film is a thin coating of plastic or wax that works to keep your coffee from seeping out and making your paper cup fall apart. Your paper cup used to feature a leak-proof clay liner, but this switched to polyethylene.
Both the wax and plastic materials make it impossible to recycle the coffee cups with regular paper items.
The fact that most paper cups now have this polyethylene coating on them is a big issue as far as microwaving them is concerned.
Different Types of Popular Coffee Cups
Despite the fact that most of your to-go coffee cups are plastic waterproofing with paper for the material, there are a few other options available for you to consider. These options include but are not limited to:
- Regular foam cups – You should never microwave these as they can easily melt.
- Styrofoam cups – You may be able to microwave this cup, but it’ll tell you on the label.
- Recycled paper cups – These cups can feature a plastic coating with glue that shouldn’t get microwaved. It could also be a fire hazard.
How to Know if it’s Safe to Microwave Your Coffee Cup
The best option you have when you’re trying to reheat your coffee is to put it in a cup that you know is safe for the microwave.
This container could be a traditional or glass mug. If the coffee cup can safely go into the microwave, it’ll say so on the bottom of the mug.
You’ll typically find labels on your ceramic drinkware, but standard disposable paper cups most likely won’t have them.
You could double-check on the manufacturer’s website if you really wanted to know about your particular cup.
The company may even put a warning that tells you not to microwave them, and you should steer clear of microwaving any cups that don’t have a warning either way.
Warning Labels on Coffee Cups
Any coffee cup that has a microwave-safe mug is one you can easily put into the microwave without an issue. You’ll most likely see this label on traditional ceramic mugs than you will on disposable cups.
You can also look for labels that say the cup isn’t safe to put in the microwave, as these labels are the best indicators on whether or not it’s a good idea to do so.
- For a microwaveable coffee cup, you want to leave the lid off before reheating it in the microwave
- Always give your reheated coffee a test stir while being careful because microwaves can cause uneven heat pockets
- Try to keep the heating time short if you’re using a plastic cup that’s safe for the microwave
Why Some Coffee Cups Warn Not to Microwave Them
Sticking your paper cup into the microwave is one quick solution to reheat your beverage. However, the risks can far outweigh any potential benefits and time you save by not switching to a different cup.
Some cups feature very thick cardboard or paper material that requires a wax coating inside the cup with glue holding it together.
The wax coating and glue aren’t suitable for heating up in your microwave because the intense bursts of heat can easily melt the wax and glue and cause them to combine inside your paper cup.
So, you’ll get adhesive and wax mixed into your coffee, and the cup may fall apart when you go to pick it up.
So, chemical contamination is a huge concern. However, the bigger issue is that it can compromise your cup’s integrity and cause the cup to leak or fully collapse.
You could end up with a mess in the microwave of glue, paper shreds, melted wax, and boiling coffee.
How to Safely Microwave Coffee Cups
You will typically enjoy drinking your coffee hot unless you chose a blended Frappuccino or an iced coffee.
If you have leftover coffee that gets cold, you can safely and effectively reheat it, but you don’t want to do it in your disposable cup. Instead, you should:
- Transfer your beverage to a cup that is safe for the microwave
- Reheat your coffee using shorter, 30-second intervals
- During each interval, you’ll carefully stir your coffee and test the temperature
- Once it reaches the desired temperature, carefully remove the coffee cup and your beverage from the microwave
- Grasp the cup by the handle and be careful so you don’t accidentally spill and burn yourself
If you don’t have a cup that is safe to put in the microwave and you don’t have a choice but to heat up your paper cup, you can follow the simple steps outlined below and use caution to reduce the chances of burns:
- Take the lid off your cup
- Put your cup inside of your microwave
- Set your power level to a low or medium setting
- Heat the cup for one-minute increments
- Stir your beverage between each minute interval
- Carefully test the temperature
- Carefully remove the cup with your beverage when it reaches your desired temperature
Be aware that microwaves are known for uneven heating and for creating larger temperature differences in the same container.
So, stirring the beverage will help disperse the heat to give you a more evenly hot beverage. In turn, you won’t overheat the coffee and burn yourself as you take a drink.
It is possible to heat a coffee cup in the microwave as long as you have a microwave-safe option. You should be very careful as you do to avoid spills or burns so you can enjoy your hot coffee whenever you like.
Ideally, you won’t try to microwave your paper or foam coffee cups, and you should pour your beverage into a microwave-safe cup.