Do’s & Don’ts for Microwavable Materials

APP Expert / Tuesday November 22, 2022


African American woman placing a ceramic bowl into the microwave.

Microwaves are so convenient for heating up your favorite leftovers, but if you’re not careful with what you warm up, you may create dangerous situations. 

Unsafe use of your microwave can lead to fires, melted materials, and fumes that are toxic or unhealthy for humans. It can also damage or break your appliance, resulting in costly repairs or replacement.

To help you utilize your appliance safely, we’ve put together a list of materials you can and can’t put in the microwave, as well as maintenance tips to keep it in tip-top shape.

At AppliancePartsPros.com, we’ve got a great selection of genuine microwave parts for your next repair. Shop with us today!

Materials You Can NOT Put in the Microwave

Let’s start by preventing microwave fires and other dangerous events. Here are all the materials that absolutely do NOT go in the microwave.

Can Metal Go in the Microwave?

No, metal doesn’t belong in the microwave, as it can cause sparks or fires when transmitted waves bounce off it. This includes common materials such as: 

  • aluminum foil
  • travel mugs (especially those with steel rims or inserts)
  • metal utensils
  • twist-ties 
  • any cookware with metal rims or inserts

Take a careful look at the cookware you place in your appliance, as many items may have hidden metallic parts that can be dangerous if microwaved. 

For your travel mug, simply heat up your coffee or tea in a ceramic mug and then transfer it to avoid the risks of metal in the microwave.

Can Plastic Go in the Microwave?

Some plastics can go in the microwave if they’re labeled “microwave-safe.” On the whole, however, it’s best to avoid putting plastics in the microwave, including: 

  • plastic wrap
  • single-use plastics, such as to-go cups
  • ziplock bags (unless labeled microwave-safe)
  • Tupperware (unless labeled microwave-safe)

To start, plastic containers and wrapping can melt and get into your food. But even microwave-safe bags and Tupperware may release microplastics called “phthalates” when exposed to heat. Studies show that phthalates can cause all sorts of health problems, including disruptions to our metabolism, blood pressure, hormones, and more. 

To avoid ingesting plastic additives like this, nix microwaving plastic altogether. Simply transfer your food to a glass or ceramic plate to heat it up. 

Can Paper Go in the Microwave?

Paper is usually a no-no for the microwave, though some specially-made packaging such as popcorn bags are acceptable to microwave. Here are different paper products you should avoid putting in the microwave:

  • paper bags 
  • paper plates, especially if they have a plastic layer or design 
  • takeout boxes, especially those with metal handles
  • cardboard packaging
  • paper towels (unless labeled microwave-safe)

Overall, paper towels can be helpful for covering food when you heat it up, but you should make sure they’re labeled microwave-safe first.

Can All Foods Go in the Microwave?

You’ll want to avoid placing certain foods in the microwave, such as: 

  • eggs with shells
  • whole fruits, including grapes, peaches, apples, pears, etc.
  • hot peppers
  • breast milk

Eggs and whole fruits get too hot under their shells/peels, which can make them explode in the microwave. If you want to heat up fruit, be sure to cut it up first and/or poke holes in the peel.

When heated, the compounds in hot peppers can become like irritating airborne pepper spray, which is why you should avoid microwaving them altogether. 

Finally, avoid putting breast milk in the microwave, for it can heat unevenly and/or leach the microplastics of a bottle. Instead, use hot water to warm up breast milk and shake the bottle to ensure it’s evenly heated.

Other Materials That CAN’T Go in the Microwave

Finally, there are other less common materials that you should avoid putting in the microwave, such as styrofoam, dry sponges, or wet clothes (especially those made of elastic or polyester).

And when in doubt, transfer your food to a microwave-safe container. It only takes a moment and you’ll guarantee the safety of your family and your appliance.

Materials You CAN Put in the Microwave

Next, let’s go through some no-problem microwavable materials so that you know what to reach for when heating up your next meal.

Can Glass Go in the Microwave?

Yes, glass is typically just fine to put in the microwave. Just be sure that the lid or design doesn’t have metal inlays. In addition, you should avoid putting in crystal or handmade pottery, which is quite fragile.

Can Ceramic Go in the Microwave?

Yes, ceramics are generally safe to put in the microwave. Again, just check that there are no metal rims or inlays.

Other Materials That CAN Go in the Microwave

Other materials may also be microwave-safe, including:

  • parchment paper
  • tea bags
  • some paper towels (check the label for microwave-safe)
  • some tupperware (check the label for microwave-safe)

When in doubt, remember to check the label to make sure it’s microwave-safe. 

Need to perform maintenance on your microwave? Browse replacement microwave parts on AppliancePartsPros.com.

Additional Microwave Do’s & Don’ts

Now that you have a good sense of materials that can and can’t be microwaved, you should consider other safety tips. It’s important to use your microwave correctly for your safety and the working condition of your appliance.

Microwave Do’s

  • Follow the instructions on the package. Often, instant and frozen meals have specific steps for how long to microwave them, so there’s no need for guesswork.
  • Leave a gap with the lid for ventilation. Make sure your plate or package isn’t closed airtight. Otherwise, the steam could overheat the food and cause an explosion. Always leave the lid with a small gap for air to circulate.
  • Check on your food and stir periodically. Be attentive to your food in the microwave. At the halfway point, you should stir or move around the food so that it heats evenly. 

Microwave Don’ts

  • Don’t add a random microwave time and setting. Most people just tap the same button to heat up meals. Instead, check the package for instructions, or set up pre-programmed cooking times for your favorite foods. This will allow for the safest and most precise heating. 
  • Don’t leave microwave foods uncovered. Don’t forget to add a microwave-safe lid to prevent splattering. 
  • Don’t let your microwave go uncleaned. You should deep clean your microwave on a monthly basis. Simply use a wet cloth to wipe down the inside. In addition, you can microwave water and vinegar to give the appliance a good scrub. Read our explanation of how to clean your microwave here!

Maintain Your Microwave With AppliancePartsPros.com

Great work, you now can identify which materials do and don’t go in the microwave!

As a part of microwave safety, you should also keep your appliance in good working order. Some key tasks you can perform regularly include:

  • Deep cleaning your microwave, especially for grease and bacteria
  • Preventing door damage by not slamming it or opening it while the microwave is on
  • Keeping microwave vents nice and clear 
  • Installing a nearby smoke detector for safety
  • Listening for unusual noises or smells, as this is a red flag that the appliance is broken

And remember: in case any repair needs come up, check out our range of genuine microwave replacement parts at AppliancePartsPros.com!

Microwave FAQs

What Happens If I Use the Microwave With Nothing in It?

Running your microwave with nothing inside it can be harmful. When this happens, there’s no food to absorb the heat waves, which then can cause damage to the magnetron. Don’t do this experiment for fun – it will only ruin your appliance. 

Can I Heat Up Wet Clothes in the Microwave?

No, you should never use your microwave as a clothes dryer. To start, your clothes may contain polyester or elastic materials that are flammable. In addition, your microwave won’t likely give you good results, as the water in your clothes will only get heated, not dried out.

What’s the Microwave-Safe Symbol?

To check if cookware, Tupperware, or other materials can go in the microwave, check the packaging for the microwave-safe symbol. This symbol shows a microwave with several squiggly lines inside. If you see it on the packaging or user’s manual, it’s safe to microwave it. 

How Should I Cover Food in the Microwave?

Ideally, you can cover food with a microwave-friendly lid. Typically, these are made of glass, ceramic or specific plastics labeled microwave-safe. Some paper towel brands are also microwave-safe. In this case, you can simply place a paper towel over the plate or bowl. 

Whenever you cover food, be sure it’s not locked airtight. Otherwise, the steam could overheat the food and cause an explosion within. Always leave a gap with the lid, or poke holes in the cover. 

When’s a Microwave Unsafe to Use?

While microwaves can last up to 10+ years if properly cared for, you should be on the lookout for an unsafe appliance. Some signs that you made need to perform a repair or replace your microwave include:

  • Unusual smells, especially of burning or smoke
  • Unusual noises
  • An unresponsive control panel
  • A door that doesn’t seal properly
  • A microwave that continues to run with the door open (as this may be a sign of radiation leakage)
  • Generally poor heating performance

If you notice any of these symptoms, you should service your microwave and perform the necessary repairs. Be sure to browse any and all microwave parts you require at AppliancePartsPros.com!

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