More and more restaurants have switched to using cardboard containers instead of styrofoam containers due to their recyclable and biodegradable qualities.
It’s no longer pizza or burger in cardboard containers but other meals as well. Restaurants can cut down on the amount of trash they produce by switching to this method, and it’s better for the environment.
Now here’s the answer to the question that you’re probably itching to ask… when you want to reheat your leftover food, can you microwave a cardboard box?
In general, you can microwave pure cardboard containers, but if the cardboard boxes contain glue, metal, ink, plastic, or wax coating, you must never put this cardboard in the microwave. This is because microwaves can cause all of those coatings and chemicals to heat up, resulting in toxic fumes or fire.
Can You Microwave Food in Cardboard Container?
Everyone loves microwaves. It is a great time-saver for those who are too busy to cook. But is it is really safe to microwave cardboard containers?
Generally, it is safe to use a microwave oven to heat food or beverages in cardboard boxes made of pure wood fiber or pulp without any additional materials.
However, not all cardboard containers are categorized as microwave-safe cardboard.
Cardboard containers with wax-coated paper or plastic wrap on the inside and take-out boxes that come with metal handles such as those found at many Chinese restaurants are not microwave-safe.
Microwaving them can cause some chemical reactions that could emit toxic fumes. The paper parts of the box may also heat up and start to smoke, which means they are combusting and may catch fire.
If you’re not sure if your cardboard container is microwave-safe, you can run your finger across the outside and inside of the food containers. If the paper is thick and stiff, it should be safe to microwave, but if the paper feels thin or flimsy at all, you shouldn’t use it in the microwave.
You may also want to check your food packaging label for any warning labels that say “it is not safe for microwaving.”
One thing you must always remember before heating food in a microwave is that you must never put an empty cardboard container in the microwave without food in them, even if the cardboard is a pure cardboard container.
Why You Should Never Microwave an Empty Cardboard Container
All cardboards have one thing in common: they are all made of wood fiber, which typically has a moisture content of between 9% and 12%.
When you microwave the cardboard, this moisture will start to drop and dry out the cardboard, and if your dry cardboards are exposed to a high enough temperature, the paper will heat up and start to burn, which can cause a fire.
When there is food in the cardboard, this process can be halted because the food will act as a barrier. The microwave energy will be absorbed by the molecules present in the food, such as the fat, water, or sugar molecules.
Meanwhile, when you microwave an empty cardboard container without any food in it, this blanketing effect is not present. More heat can travel into the cardboard, which exposes it to higher temperatures than would be expected if there was food inside.
Also, if there is any metal or other coatings that are not mentioned on the food package label inside this kind of box, they can react with the microwaves and create a spark.
In short, never microwave an empty cardboard container, make sure there is food inside the box before placing it in the microwave oven.
Digging Deeper Into the World of Cardboard
There are different types of cardboard and cardboard products being used for all kinds of packaging purposes. Based on the materials, the cardboard can be differentiated into two categories: corrugated cardboard and cardboard box.
Corrugated cardboard is made from three layers of paperboard which makes it stiffer and stronger than traditional cardboard. It consists of an inside liner, an outside liner, and a fluted corrugated sheet in between.
Because of its high strength-to-weight ratio, corrugated cardboard is often a more preferred solution for shipping, packaging, or storing medium-sized and large items like household appliances and not surprisingly for food containers such as cardboard pizza boxes.
There are at least three reasons why corrugated cardboard is a better choice over traditional paper-based products to make a pizza box. First, it’s rigid and light. Second, its ribbed structure provides better insulation for your pizza and so it retains the pizza’s heat better. And lastly, it absorbs fat and grease from the pizza.
Traditional cardboard box is made from the same material as a corrugated board but it is only a single layer of heavy-duty paper or paperboard.
This type of cardboard isn’t as durable or strong, but it’s cheaper to make than corrugated board so this makes sense why they would be used to package smaller items like cereal boxes, board games, and other similar objects.
Even though corrugated cardboard is more heat resistant and stronger than traditional cardboard, it is still very combustible.
For this reason, I would still recommend not to reheat your food directly in the microwave if you are using a cardboard container. Instead, it’s better to place your food in an oven-safe dish or bowl before placing it in the microwave.
Tips to Microwave Cardboard Safely
Now we know that you can safely microwave cardboard but with some caveats. Here are some tips to keep in mind when microwaving cardboard:
- Avoid using cardboard containers with metal handles, as the metal can cause sparks.
- Ensure that the cardboard container has no styrofoam and plastic parts or plastic and wax coating.
- Always make sure that there is food inside the box before placing it in the microwave oven.
- Ensure that the microwave is set at a low power setting and keep an eye on it closely to make sure there are no sparks or flames.
- Be aware that some inks and dyes can cause sparks or fires in the microwave.
How Long Can You Microwave Cardboard?
You might be surprised to learn that you can microwave certain types of cardboard. Still, there are some limitations on how long you can microwave your food in a cardboard container before it starts to break down or melt.
According to most instructions that I found in most microwave-safe labeled cardboard containers, it is safe to put cardboard in the microwave for up to 120 seconds. Some foods may require longer durations to heat up.
For example, foods that contain more water content like soup will heat up longer than foods with less water content like rice. If your food needs more time in the microwave, it is best to microwave it in short 30-second intervals.
What is a Better Replacement for Cardboard for Reheating Food in Microwave Oven?
What is a better replacement for cardboard when reheating food in the microwave oven?
When it comes to food safety, the better option is to use heat-resistant ceramic or glass dishes. These are also microwavable and can be used safely in an oven as well! Microwave-safe containers with lids make reheating leftovers easy – just store your dish at room temperature until ready to use.
While you’re shopping for the right microwavable dish, look for one that has a good seal and is large enough to contain your leftovers with space around it, so items don’t get overcooked or burnt in the corners of the container. A lid will prevent splatters when reheating food too!
Putting cardboard in the microwave oven is a great option to reheat food without dirtying dishes and creating excess cleanup.
However, there is one important thing to keep in mind before microwaving anything made of cardboard.
Make sure the cardboard is made up of pure cardboard and that it doesn’t have any plastic coating or wax on it before microwaving. If it does not meet these criteria, don’t put it in the microwave!