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Can You Put Styrofoam In The Oven?

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Styrofoam is a lightweight material used to make food containers and cups. These items are widely used in restaurants and you have probably taken some food home in a styrofoam container.

But you may have wondered: can you reheat food in these containers?

Can you put styrofoam in the oven? You should never put styrofoam containers in the oven. Styrofoam, made from expanded polystyrene doesn’t withstand high heat. It will start softening at 212°F and melting at 464°. You can use styrofoam containers to preserve food in the fridge but never reheat or cook with them in the oven.

In this article, you will learn all about styrofoam, how it reacts with heat, and what are the safe ways of using styrofoam items. 

What Is Styrofoam?

The term Styrofoam is trademarked by The Down Chemical Company, which manufactures Styrofoam through the extrusion of polystyrene foam. 

In the United States, the word styrofoam refers to a kind of expanded polystyrene. 

Before getting into what polystyrene is and how it makes styrofoam, let’s go over the differences between extruded polystyrene and expanded polystyrene:

  • With extruded polystyrene, the manufacturing process includes mixing it with other ingredients by melting them together. 
  • For expanded polystyrene insulation, heat or steam is applied to the molds filled with polystyrene beads. This causes them to expand and stick together. 

Polystyrene is a plastic material used in the manufacturing of numerous products used on the daily. It is derived from the monomer styrene. 

When turned into a foam-like material, polystyrene is most valued for its cushioning properties. This kind of polystyrene is around 95% air, which makes it buoyant. 

If you take a close look at a piece of styrofoam, you will see the numerous white spheres. These are the particles that have been expanded to form a particular object, be it a cup or a box. 

Polystyrene beads are way smaller than already expanded spheres you can see in a piece of styrofoam. If you have these beads at hand, you can do a few easy experiments to get a clear idea of how styrofoam is made. 

Put these beads into some kind of a metallic mold that you can close tightly. Don’t stuff the mold with beads but only fill 1/3 of it with them.

Boil the mold for a few minutes. Take the mold out and let it cool. Once you open it, you will see that the beads have expanded significantly. 

Polystyrene beads will also expand if you microwave them with a small amount of water or steam them. 

What Is Styrofoam Used for?

Styrofoam is used in many to-go food containers, plates, and cups. This kind of packaging is lightweight and convenient for storing cold food.  

You have almost certainly gotten your food delivered or picked up in a styrofoam container. It’s quite ubiquitous these days.

What Temperatures Can Styrofoam Withstand?

If you have ever held a styrofoam container in your hand and felt how lightweight it is, you may be concerned about putting it somewhere hot. It feels like the box will melt away immediately. 

What is the Melting Point of Styrofoam?

As we have already mentioned, styrofoam is expanded polystyrene beads. The temperature at which these beads melt is 464 °F (240 °C).

However, styrofoam containers will start softening way before the heat reaches this degree. 212°F (100°C) is enough to soften containers made from this material. (That’s only the temperature it takes to boil water!)

Taking this information into account, it is recommended to be very cautious any time you have a styrofoam object near heat. 

Can You Put Styrofoam in the Oven?

As you have probably guessed, you can’t put styrofoam in the oven and there are two hefty reasons for it:

  1. Styrofoam containers don’t take the heat well. As we said, they will start to soften at 212°F (100 °C). To reheat food in the oven, you will need to set it at an average heat setting, which is typically going to be around 320 to 350 °F. Trying to reheat food in a styrofoam container at a temperature lower than 212°F will be pointless, ruining the box and probably your food.
  2. Even if you could put styrofoam in the oven, you are never recommended to eat hot food from Styrofoam containers.

While some restaurants may put hot food in styrofoam containers and eating it a couple of times won’t cause irreversible damage, you should certainly avoid doing it when you are at home and can easily transfer your food into a suitable container. 

What Happens When You Put Styrofoam in the Oven?

If you put a styrofoam container or cup in the hot oven, it will start to discompose. 

Leaving Styrofoam in the oven at high heat will cause it to melt and turn into a soft and sticky mass. Some oil may come out of burnt styrofoam as there is styrene in it. The latter is an organic compound and is an oily liquid. 

For this to happen you will need your oven to be very hot, reaching the melting point if polystyrene. 

Safe Materials for Reheating Food in the Oven

There are multiple options for oven-safe materials. Here are some of them. 

  • Metals: Cast iron and stainless steel pans are safe to be used for reheating food in the oven. 
  • Glass: Oven-safe glass dishes are another great option. The best part about these dishes is that you can also serve the food in them. Don’t use pans that have plastic or wood details on them. 
  • Ceramics: Ceramic dishes can also be put in the oven. However, always make sure to check the label to see if the particular dish is oven-safe. 

What If You Accidentally Burn Styrofoam?

Styrofoam releases dangerous chemicals when burnt. The gas and chemicals that burnt styrofoam releases are toxic to the environment.

Not only that, they can also damage your health as well. Adversely affected lungs are one example of the damage burning styrofoam can cause.  

But don’t be startled if you have left a styrofoam container in the oven to heat a takeaway meal once. Burning styrofoam once will not cause major damage to you or the environment. 

What Happens When You Microwave Food in Styrofoam?

If you are still hoping for your favorite kitchen appliance to come and save the day, please stop for your own sake. It is often not recommended that you put styrofoam in the microwave either. 

As styrofoam containers are predominantly made of polystyrene, they will and soften release chemicals just like they would in the oven. 

It should be noted, however, that microwave-safe styrofoam has been developed to withstand the waves in the oven and this material will be safe to eat food from. You just have to be sure that’s what you have.

Microwave-Safe Styrofoam – What Is It?

Traditional styrofoam containers are not safe to be used in the microwave. However, there are microwave-safe styrofoam containers on the market to make things easier and safer. 

These types of styrofoam containers are made with safer materials and don’t release chemicals when heated in the microwave. 

With this being said, you should never assume whether the container is microwave-safe or not. What you should do is checking to see a label clearly stating that the container or cup is safe to be used in the microwave. 

If you can’t find the label, err on the safe side and reheat your food in another container that you are sure is microwave-safe. Better safe than sorry!

Microwaving Food Safely 

If you are still on the fence whether you should put styrofoam in the microwave, do it in the safest way you can following these simple rules:

  • Transfer the food from the styrofoam container into a plate or a container that is microwave-safe. 
  • Don’t leave metal utensils in your food to not cause any sparks. 
  • Spread the food on the plate to heat it evenly and reach a safe internal temperature. 
  • Stir the food or rotate the plate when reheating very cold food in order not to leave any cold spots as they may contain bacteria. 

What Should You Use Styrofoam Containers For?

Styrofoam containers are great for storing cold food. You can put your leftovers in a styrofoam container and store it in the fridge. 

Styrofoam cups can be used for cold drinks. Avoid using these cups for hot drinks. While styrofoam cups are said to keep drinks hot longer and are comfortable for holding, they are not recommended for use with any hot liquids

Use paper cups for hot drinks instead. They are much safer. Plus it is much easier to recycle paper cups. 

You should also avoid using styrofoam containers for acidic food. A hot dish with a tomato sauce, for example, shouldn’t be consumed from a styrofoam container. 

This suggests that drinks with high acidity levels, such as citrus juices and cocktails, should be drunk from cups made of other materials. Glass cups, for example, are an elegant and sustainable choice. 

You may even want to avoid using foam polystyrene cups for alcoholic drinks, as well as bowls, plates, and containers for oily food. 

In a word, you can use Styrofoam containers and cups for anything that is not acidic, oily, alcohol-based, or hot. 

Up Next: The 5 Best Oven Safe Skillets

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