Have you ever found yourself in the middle of a rush to reheat your lunch and you think to yourself, “Can I just put this cardboard container in the microwave?” We’ve all been there. Cardboard is frequently used to package food and takeout items, but can it withstand the heat from your old faithful microwave?
The Basics of Cardboard
Cardboard can be naturally brown or bleached white, and is 100% recyclable. It’s lightweight, cheap and eco-friendly, which makes it one of the favorites for packaging and storage. You have no doubt come across cardboard in all of its multifarious guises, including pizza boxes and cereal boxes, but also different sizes of shipping box.
How Microwaves Work
Microwaves operate by emitting electromagnetic waves that agitate water molecules in food. The excitement creates heat, and your meal warms up in minutes. Microwaves are tremendous workhorses for heating food — if you use them correctly — however, they’re not without their idiosyncrasies.
Microwaves and Cardboard
So, is it safe to microwave cardboard? It depends, is the short answer. Not all cardboard is microwave-safe, and some is microwaveable while some is not.
Coated or Plain Cardboard: Coated and uncoated plain cardboard are usually ok for microwaving. But it’s not the greatest option because it’s prone to sogginess, particularly when there is any moisture (like the steam wafting off your dish). If it’s at all possible, you want to transfer your food to a microwave-safe glass or ceramic container.
Plastic-Coated Cardboard: Certain cardboard cartons feature a thin layer of plastic or wax to make them more resistant to water and oil. Microwaving such containers can result in the coating melting, which can pose risks to human health. It’s better to err on the side of not microwaving anything that has a coated cardboard surface.
Printed Cardboard: If your cardboard box has printed on it, then beware. In the printing inks, there could be metal particles that spark in the microwave and start a fire. If you prefer, transfer it to a microwave-safe dish.
How to Microwave Cardboard Safely
If you are stuck and need to microwave cardboard, there are a few things you can do to ensure it comes out fine:
Look for Coatings: Check the cardboard for wax or plastic coatings. You should avoid microwaving it if you see any.
Remove Staples and Tape: If your cardboard has staples or tape attached to it, remove them prior to microwaving. Metal items placed in the microwave can spark and create a fire hazard.
Microwave Plain Cardboard in Short Bursts: If you need to microwave plain cardboard, make sure to heat it in short intervals to prevent it from being exposed to much heat and moisture.
Don’t Take Your Eyes Off: Never take your eyes off the microwave when heating cardboard, in case anything unexpected happens.
Other Alternative Methods to Heat Cardboard
You can decide to use plain cardboard in a pinch, but it’s not the greatest. There are safer alternatives:
Microwave-Safe Containers: To reheat your food, a microwave-safe glass, ceramic, or plastic dish works best.
Transfer the Food: If your leftover is in a cardboard container, pour it into a microwave-safe dish before heating.
Oven or Stove: Reheat your food the old-fashioned way for the best chance at retaining its quality.
So, is it possible? Yes, just not as safely or efficiently. Uncoated, plain cardboard may be microwave-safe, although it is not ideal, so always transfer your food to a microwave-safe dish if you have one. Be sure to use care when working with coated or printed cardboard in order to mitigate potential hazards. Microwaves work wonders in reheating food, but safety always should be a priority, especially when using cardboard.
