A microwave oven is an indispensable part of the fast-paced life most people lead these days. To quickly heat or prepare food, a microwave comes in handy.
The food however needs a container to be stored in while it is being microwaved. People look to glass bowls, as they are quite sturdy, and wonder if that is a safe enough choice of utensil to put inside the oven.
Well yes, a glass bowl can indeed be put inside a microwave oven without any damage to the bowl or to the oven.
Most metals cannot be microwaved and there have been many unfortunate accidents with wrong utensils and microwaves. This is not the case with glass bowls, as long as you are using the right kind of glass.
Can You Microwave A Glass Bowl?
Yes, you can microwave a glass bowl. On many accounts, it is considered safer than using plastic bowls, even if the plastic is of superior quality and from trusted brands.
This is because putting a glass bowl in the microwave removes all chances of the food being tainted by the release of a harmful chemical called BPA that is present in plastic containers.
However, despite being safer than plastic bowls, not all glass bowls cannot be used for microwaves.
Many consumers have complained of a cracked glass utensil that they used to heat or cook food inside the microwave and this can be attributed to the fact that the glass they used was not suitable for the microwave oven.
There are many kinds of manufactured glass on the market and not all of them are microwaveable. The surest way to know if you can microwave a particular glass bowl or not is by checking if it has the microwave-safe label or not. If not, you can just learn a bit about different types of domestic-grade glasses to help you.
Natural glass is usually sturdy and can undergo heat without cracking. Cookware made of natural glass is common in households because of its resistance to heat.
But the thing is, it cannot be exposed to large amounts of heat for a long time or it might crack.
This means, you can safely heat the food inside the bowl but you cannot cook or bake inside it.
Synthetic glass on the other hand is a laboratory-made version of manufactured glass that can withstand high amounts of heat without showing the least bit of a crack. There are two types of synthetic glass available in the market – borosilicate and soda-lime.
The borosilicate is considered to be more sturdy as it contains 15% boron trioxide which practically makes it resistant to sudden and extreme temperature changes. To put it simply, a glass bowl made of borosilicate will not crack even if you bring it out of the oven and place it in chilling cold water.
Soda-lime glass does not make good microwaveable bowls because it expands twice as fast as borosilicate glass when exposed to heat. It will break down and shatter very fast if one were to place it in the oven and turn the temperature on high.
Pyrex glass is often a popular choice for a microwaveable bowl but pyrex is nothing but the name of a brand that deals in synthetic glass. For many years the name Pyrex and Borosilicate glass have been used interchangeably, that is until the company also started manufacturing products with soda lime glass.
Ceramic glass bowls, colored glassware, and glass bowls with metallic trims are also unsuitable and unsafe to be used inside a microwave oven.
What Happens If You Microwave A Glass Bowl?
When you put a glass bowl inside the microwave, like every other object that comes in contact with it, the glass bowl starts to conduct heat. The heat spreads along the body of the glass and makes it expand.
This rate of expansion determines whether or not a glass bowl is safe and sturdy enough for a microwave. The glass that expands very fast will fast lose its structural integrity and crack or shatter.
Borosilicate glass is preferred due to this very reason, it conducts heat very slowly and not only does it expand very slowly but also keeps the surface of the glass bowl from getting very hot.
Complaints of glass bowls that have broken or cracked after being microwaved or while being microwaved have often been heard and it can only happen due to a few reasons.
The glass bowl that was used may not have been microwave safe and thus cracked under the heat generated inside the microwave oven. Or even if it was microwave safe, maybe using it for a second time without letting it cool down from the first time could have caused it as well.
Another reason why the glass bowl might have cracked as that it was already impacted before.
Thermal shocks can also crack a glass bowl if it is not made of sturdy material like borosilicate.
Not all thick glassware is synthetic borosilicate and while they have good resistance to heat, the same cannot be said about their resistance to sudden changes in temperature. Quick successions of expansion and contraction will obviously lead the bowl to crack.
Is A Glass Bowl Microwave-Safe?
A glass bowl is microwave-safe but not all types of glass bowls are resistant to heat and thus cannot be called a microwavable glass bowl. The ones that come with the label and only very thick or borosilicate glass bowls can be microwaved without the possibility of any damage.
Such glass bowls are considered not only safe but also the most recommended choice of kitchenware for microwaving purposes. This is because, unlike plastic, it does not release BPA into the food which has some legitimate negative effects on human health if consumed regularly.
Moreover, there are many risks associated with using an unsuitable material inside the microwave as it may at the very least result in unevenly cooked food and at the worst cause a fire hazard as well as a damaged utensil. This is the case with metals, which should absolutely not ever be microwaved as they will cause a fire when exposed to high temperatures.
Glass bowls do not pose this problem as the distribution of heat in microwave-safe bowls is slower compared to other materials.
This automatically means that these bowls do not expand at an alarming rate when heated and thus can safely endure extreme heat. This means it will not crack from baking a cake inside the microwave oven which takes a minimum of thirty minutes at a considerably high temperature.
A glass bowl is considered a safer choice also because it can take thermal shock well and adjust to different changing temperatures.
How Can You Tell If A Glass Bowl Is Microwave Safe?
The surest way to tell if a bowl is microwave safe or not is to see whether or not it has the label containing the symbol for microwavable. But if there isn’t one, you can still check for yourself and see whether a bowl is microwave-safe or not.
Follow these steps to perform the microwave ability test on a glass bowl :
- Fill the glass bowl with water. The water should not be hot or lukewarm. It should be room-temperature water but on the cooler end of the temperature scale.
- Set the microwave to its highest powered setting. It may vary between different brands of microwaves but the difference will not be so huge as to cause any noticeable change in results.
- Turn on the microwave and let it run for a full minute.
- After the minute ends if the bowl is hot to touch and is scalding your skin then it is not microwave safe. However, if the bowl is not hot but the water inside has warmed up, then you can safely mark this bowl as microwaveable.
This is often called the microwave test and efficiency checks the resistance of any utensil to heat from the microwave oven.
The bowl that will heat up first will not probably crack if exposed to the same highest-powered setting for a bit longer than one minute, but it will also not cook/heat the food evenly even if the heat is lowered.
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Safety Tips: Things To Know Before Microwaving A Glass Bowl
Since the microwave oven is an electrical appliance that also generates a large amount of heat, it is always wise to read up on the safety precautions of operating the device.
Similarly, there are some safety tips that you should follow if you use a glass bowl for microwaving food.
The Bowl Lid Should Not Be Too Tightly Fastened
Most glass bowls that are bought as microwavable kitchenware will have a lid but even if it is not, it is advisable to purchase a glass lid for the bowl. Microwaving food with a lid on ensures even cooking of the food from the heat that is trapped inside the bowl.
However, this very lid should not be fastened too tightly or else the trapped water vapor won’t come out and will exert pressure on the side of the bowls causing it to crack.
This is of course not true for all types of food. If you are baking a cake, you cannot cover the bowl with a lid as the batter will expand and the lid will only block its path.
Do Not Immediately Reuse An Already Hot Bowl
That is to say that if you have used the microwave-safe bowl to cook or heat something, do not immediately put it back inside for a second time to heat more food.
Although borosilicate glass bowls will not be damaged even on being exposed to high heat, one should still not risk it.
You can instead use the feature of thermal shock sensitivity to your advantage and drain the heated bowl in cold water to cool it down faster. In this way, if you are in a hurry you can reuse the bowl without risking damage.
Do Not Microwave Glass Bowls With Metal Rims
As we have already discussed, metal should never be put inside the microwave as it will cause a major fire hazard and also crack the bowl in question.
Check The Glass Bowl For Previous Cracks And Dents
Although glass bowls are pretty sturdy materials, they can still get impacted by getting hit somewhere hard or being dropped.
The impact will manifest in the form of a visible fault line along the body of the glass bowl.
Such a glass bowl, no matter how microwave-safe, should not be used for microwaving food as on being exposed to heat, it will expand and the crack will increase causing the bowl to explode inside the microwave.
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Therefore, as it stands now, glass bowls are perfectly safe to be used inside a microwave as long as you are using the microwavable ones or the one with a microwave-safe label.
Not all glass cannot be microwaved and you should especially avoid those glass bowls that are rimmed with metal or decorated with it. Metal and microwave ovens are not a good combination and no one should risk it.