Understanding The Microwave Safe Symbol | What It Actually Means?

understanding microwave safe symbols

Microwaves are often the unacknowledged items of utility that are used more than any other item in your kitchen. The biggest problem, however, is that not all containers are microwave-safe. No matter what age you are, microwaveable containers are usually a mystery that nobody can seem to comprehend. 

One-too-many kitchen hazards are caused by microwaving the wrong material. To avoid accidents in the kitchen, though, you need to double-check to make sure of what you’re microwaving. 

The varieties in containers can be deceptive. A great way to tell whether something is “microwave safe” is checking if it has the microwave-safe symbol on it. No more guesstimating whether your container is safe to be put in the microwave or not! Enforce kitchen safety and make the most out of your cutlery and containers.

Is There A Standardized Universal Microwave Safe Symbol? 

microwave oven safe symbols

Short answer – no, there is no one standardized universal microwave safe symbol. There are several such microwave-safe symbols that are usually on the bottom of pots, pans, containers, bowls, or anything else that holds food. But the good news is that these symbols look very similar.

These symbols usually consist of wavy lines inside a microwave-shaped rectangular box. It can also include the word “micro”, but the wavy lines are a constant so you don’t have to worry about these differences. Recently, most microwaveable cutlery and containers also have warnings like “not safe for microwave” written on them, so you might want to check your container thoroughly to make sure. 

What Does ‘Microwave Safe’ Mean?

To understand what the phrase “microwave safe” means, we first need to understand how a microwave works. This device heats up your food through the magic of physics – it releases “microwaves” into your food, which then become attached to sugar and water. The heated sugar and water then heat up the rest of your food, which, in turn, heats up your container as well. Visit this brief article to completely understand the working of microwaves. This principle stays same for all types of microwaves including built-in oven microwave combos and drawer microwaves. Basically any microwave configuration that use a magnetron as their primary apparatus of function.

Any container that is not negatively affected by this heating can be considered fit for the phrase “microwave safe.” 

However, some containers can melt, overheat, or even char or arc and create fire hazards with the heat from the microwaves. Arcing of microwaves isn’t however always because of the material used. Rust or exposed metal inside the cavity can be a very likely reason too. These materials contain compounds that may melt or release hazardous fumes into your food. These materials, hence, are decidedly not microwave-safe and should be avoided at all costs. On the other hand, materials that are specifically made to take high temperatures of microwaves are a-okay to use! Here’s a brief rundown of what these materials are. 

What Materials Are Generally Microwave Safe? 

what materials are microwave safe

There are some products that belong in your microwave. These products have been built with specialized materials that do not react to heat and can thus withstand high temperatures with ease. Here are a few products that you can trust to be microwave-safe:

1. Glass

While glass may seem daunting as it is such a fragile material, almost all forms of glassware can be safely put into your microwave. Most glass that is used in crockery and cutlery is meant for microwaves and can be used to reheat food anytime. These can also be used for baking purposes. 

Borosilicate glass, especially, is a more durable form of glass that absorbs high quantities of heat. If your glassware is made of this kind of glass, then you can rest assured and use them in the microwave anytime. 

However, it would be best to avoid thermal shock with glassware. The biggest danger to glassware comes not from the high temperatures of the microwave – it is if you accidentally douse a hot glass object in cold water or vice versa. Be careful with that!

2. Plastic

While the jury is still out with the decision on that one, plastic that is specifically intended for the purposes of microwaving (such as polypropylene) can be trusted. Most forms of plastic used in containers such as Tupperware and Ziploc are specially meant to store and heat food, so you can microwave them with reassurance. 

However, some forms of plastic can melt when in the microwave, so exercise caution here! Look out for the microwave-safe symbol on plastic.

3. Ceramic

These are excellent for microwave purposes. Ceramics that have been made in recent years have labels of being ”microwave safe” so you definitely trust them. 

However, ceramics that have detailed designs on them can be unsuitable for microwaves. These designs can unwittingly trap heat inside them, overheating the whole pot. Ceramics that have been made at home as well, unless fired at extremely high temperatures during the process, can be a strong “maybe” when it comes to putting them in the microwave.

4. Paper

While paper seems like something that would be highly flammable (and it is!), it’s the contrary in microwaves. As we said before: microwaves act on substances with fats, sugars, and water. Paper that is specialized for microwaves contains none of these substances. Paper used during the cooking process – parchment paper, wax paper, and paper plates are completely okay to use in microwaves.

The exceptions to the safety rule are newspapers since they are capable of leaking ink and getting it on your food. Brown paper bags are also not recommended in microwaves, since they’re more fragile.

These materials are generally more microwave-safe than others and even say so in their packaging. Most of the products made out of these materials sport the symbol for being “microwave safe” so you’re good to go on these ones.

What Materials Are Not Microwave Safe? 

what materials are not microwave safe

On the other hand, some materials should definitely stay as far away from that microwave as possible. 

For instance, most metals should be allowed nowhere near microwaves. There are many cases of people unwittingly putting metal containers into the microwave only to learn against it the hard way. Scary. Metal bowls, containers, pots, pans – especially anything with a curved or non-flat surface – can trap microwaves in them instead, causing heat to explode all at once when given an outlet. It is best to avoid all forms of metal in the microwave. 

Containers with metal trims at the top can overheat , so remember to check your container for any traces of metal carefully. 

One-time use plastic can be your microwave’s worst enemy as well. As the name suggests, these forms of plastic are disposable and have extremely different compositions from microwave-safe plastics. They can melt into your food and ruin it completely. 

Perhaps the most important – aluminum foil. This material is the worst for microwaves and can not only char the food inside it to bits but also risk a fire hazard for your whole house. Definitely try to stay away from this one. Other substances of similar composition such as candy wrappers should also not be allowed to interact with microwaves. 

How to Know If Something Is Microwave Safe 

Usually, the container has a warning that says “safe for microwave” or “do not microwave.” If not, there might be a microwave-safe symbol telling you whether it is microwave-safe or not. If the container lacks both of these things, then you’re going to have to take it up from here.

Take the container that you’re unsure about and try heating up some water in it for a minute. If after a minute the container is extremely hot to touch, it’s best to not attempt to microwave it for longer durations. Do this exercise only if the material does not fit the obvious description of it not being microwave-safe!

Frequently Asked Questions

Yes; most styrofoam containers have the “microwave safe” label on them and have been tested by the FDA as microwaveable as well. However, styrofoam is known to contain certain compounds such as styrene that may be considered toxic (the studies are as yet inconclusive). We recommend you to not microwave styrofoam unless explicitly stated otherwise.

Most melamine containers are completely safe to use in the microwave! However, you might want to check if your melamine container is older. Only recent melamine products have been optimized for microwave use, so we recommend you make sure your older melamine is safe by checking for a microwave-safe label of any kind. If you don’t find one, it’s best not to risk it.

Lucky for you, most Tupperware products are microwave safe! So, most of the products have the “safe to microwave” symbol or label over them as well. Additionally, Tupperware is also free of BPA – a chemical that could be potentially harmful to your food. However, Tupperware products that are not microwave-safe have no such microwave-safe plastic symbol on them, so avoid those products in the microwave.

Yes, all forms of Pyrex are completely safe to be put in the microwave! Pyrex is usually made from borosilicate glass, making it more resistant to heat than other forms of glassware on the market. Pyrex can be used both in an oven and a microwave, making this an all-around safe option. 

We would not recommend putting a mason jar in the microwave. While opinions have been divided about this trendy drinkware, it is best to not risk it. The lids of mason jars are usually made out of metal, and we’ve already talked about why that’s a bad idea. However, you can heat liquids for short amounts in a mason jar (but only with the lid off!).

This is a bit of a mixed answer. But paper plates that are made completely out of paper should be safe to put in the microwave. This goes for all other forms of paper too, as paper is not reactive with heat. However, paper plates that have a small film of plastic on them may be unsafe – and since there’s no real way of making sure that it’s microwave-safe plastic, paper plates coated with plastic should be avoided.

Ziploc bags are safe to microwave food in, but conditionally. All Ziploc bags begin to melt at higher temperatures such as 90-degree celsius. You can choose to defrost food or reheat it in a Ziploc bag, but keep in mind to set the temperature of the microwave to below its melting point. 

As goes with most forms of ceramic, porcelain is also completely microwave-safe. While surfaces of porcelain products may begin to get extremely hot, they don’t stand the risk of overheating. However, porcelain products with intricate details or designs should be avoided – as these risk trapping heat. 

Parchment paper in microwaves is definitely safe! Like most forms of paper, this one is even more specialized to withstand high amounts of heat all at once. This is the least reactive form of paper, which is why it is widely used in baking. It also does not stick to surfaces, making it the ideal form of paper in microwaves. 

Verdict | Always Look For Microwave Safe Symbols

While there are some products that definitely belong in the microwave while some definitely do not, there may be some that exist in the gray area of being “microwave safe”. 

Hence, to avoid risking it, trust the microwave-safe icon on your products. If you don’t find any symbols or labels, then do not microwave them. Chances are that it is highly reactive to heat and runs the risk of overheating, burning, melting, or worse – incapacitating your microwave for good. This stays true for standard microwaves as well as their convection-based counterparts.

Presently, most products have warnings that advise you against microwaving a product if it is not meant for high amounts of heat. Remember to check any new products – before purchase – for the wavy, parallel lines (or similar variants of the symbol) that can reassure you about their microwave-ability. Rest assured against untoward accidents in the kitchen!

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