Can You Put Cardboard in the Microwave?

You may want to put cardboard in the microwave for several reasons, such as drying or reheating food. In any case, you can heat some kinds of cardboard, but not all. 

It would be best to take precautions before heating your cardboard to ensure it is safe to reheat, like checking the label. 

The cardboard will likely catch flames after reaching temperatures of 400°F or 205°C and above. 

Can I Put Cardboard in the Microwave?

You can put most cardboard in the microwave for short periods. Some sorts of cardboard are not microwave-safe. Cardboard can be highly flammable, especially at temperatures over 400°F. If the label on the cardboard box states that it is microwave-safe, you should be safe to microwave it. 

You should never microwave cardboard with metal, wax, glue, ink, or plastic. You can microwave a few sorts of inks. The ink should be safe if the label states that the cardboard box is microwave-safe. Always heat at your microwave’s lowest setting for the most promising results. It is best to check the temperature every 30 seconds. 

It is always better to microwave in a microwave-safe container instead of cardboard to lessen the risk of fires. Another thing to mention, you should never put cardboard alone in the microwave. Cardboard with no food or drink in the microwave will catch blaze. 

What are the Effects of Putting a Cardboard in the Microwave?

There can be effects of certain types of cardboard. Some cardboard will have metal, wax, plastic, or ink that could be toxic to you and your health. The microwave may have some damaging effects on cardboard. 

As you may know, a microwave generates electromagnetic wavelengths, called microwaves, between infrared and radio waves. A magnetron is the built-in vacuum line that every microwave has. This tube is what is responsible for generating microwaves at the 2450 frequency. 

When this vacuum tube creates the 2450 frequency, the molecules of your food start to vibrate and rotate, causing them to interact with each other. This interaction generates heat and warms your food or drink. 

What Types of Cardboard Can and Can’t Be Microwaved

A general rule of microwaving cardboard is only microwaving as long as it is all cardboard. As mentioned earlier, only certain sorts of cardboard can safely microwave. Take a peek at the list of safe and unsafe cardboard to microwave. 

Can Microwave

  • Cardboard that is free of metal. Metal is a no-go in the microwave. 
  • Pure cellulose cardboard, no additives. Additives could catch fire in the microwave. 
  • Cardboard that has no plastic or wax. Plastic or wax could leach toxic chemicals into your food. 
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Can’t Microwave

  • Cardboard with glue or adhesive of any kind. Adhesives will release chemicals into your food. 
  • Ink-printed cardboard. Ink will leach chemicals into your food when heated. 
  • Wax or plastic-lined cardboard. It will leach toxic chemicals into your food. 
  • Takeout container with metal handle. Metal does not go well in a microwave. 

How to Tell if a Cardboard is Microwave Safe?

There are ways you can tell if the cardboard of your takeout is microwave-safe. The most painless way to determine if your cardboard is safe to microwave is by looking for a microwave-safe label. 

Most microwave-safe containers will have a label clearly stated. If there is no label, you should not take your chances. Transfer your food to a plainly labeled microwave-safe container for reduced fire risk. 

What are the Things to Know Before Microwaving a Cardboard?

There a key points you must keep in mind before microwaving cardboard. Whether checking the ability to microwave or monitoring your food, it is all helpful. 

Check to Ensure the Cardboard is Microwave-Safe

The number one rule of microwaving cardboard is ensuring the cardboard is safe to microwave. If your cardboard is not microwave safe, you could release toxic chemicals into your food. These harsh chemicals could make you ill. Symptoms can include: 

  • Nausea. 
  • Vomiting. 
  • Headache.
  • Loss of appetite.
  • Chills.
  • Fever. 
  • Other flu-like symptoms. 

Symptoms could clear up on their own in minor cases. More severe cases may not improve, and you may need medical attention. In some extreme cases, harmful chemicals could cause death. However, that is unlikely to happen from microwaving a single piece of cardboard. You would need to consume a lot more to get that ill. 

Line Your Cardboard With a Paper Towel. 

Lining your cardboard with a paper towel or napkin is one of the best ways to avoid problems when reheating your food. When reheating cardboard, it would be a good idea to line it with a paper towel or napkin. Doing so will prevent your cardboard from catching flames. 

The paper towel will remove the excess oils and grease. Fats and grease can speed up the reheating process of your food; this could cause it to catch blaze. No one wants their microwave catching on fire; that can be a costly mess. 

You want to avoid cleaning up after a microwave fire, let alone pay for a new microwave. 

Monitor Your Food 

The best thing you can do when microwaving cardboard is monitor your food and cardboard for the entire reheating time. It would be best if you never left cardboard unattended in the microwave. 

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Cardboard can catch flames and start your microwave on fire in less than a few minutes. Watching your food in the microwave can ensure that your cardboard will not go up in flames. Leaving your food unattended could end badly for you and your microwave. 

Frequently Asked Questions

If you need more clarity on microwaving cardboard, you may refer to the frequently asked questions. Many people have the same questions when it comes to microwaving cardboard. 

Is cardboard toxic when heated?

You should always ensure that the cardboard you are attempting to reheat is safe to put in the microwave. Cardboard can be toxic when heated if it is not microwave-safe or has printed ink on it. 

Certain types of cardboard will either catch flames or leach chemicals into your food. Either one is not much fun. 

What temperature will cardboard burn?

You must monitor your food and cardboard to ensure it does not catch fire. Every type of cardboard will catch fire if it hits the right temperature. In the microwave, you can achieve that temperature quickly. 

After the cardboard reaches a temperature of 400°F or 205°C, the moisture levels of the cardboard will drop. With no moisture, your cardboard can easily catch flames. 

How long can you heat a cardboard box in the microwave?

You should never microwave a cardboard box with no food. If you microwave just the cardboard, it is much more likely to catch flames.

 It would be best if you microwaved your cardboard in 60 to 120-second intervals without taking your eyes off it. You should also check the cardboard to ensure it is not getting too hot every 30 seconds. 

To avoid issues, constantly monitoring your microwave at the lowest power level is your best bet. Remember that cardboard is more likely to catch fire at temperatures of 400°F or 205°C, so ensure you check that it is not getting too hot in the microwave. 

Final Thoughts

To sum it up, you can put cardboard in the microwave with little risk as long as it is microwave-safe, pure cellulose, and has no printed ink. Some kinds of ink are okay to be reheated. However, always check the cardboard for a safety label to ensure it is safe to heat.