Can You Put A Thermos In The Microwave – Manufacturer Answers

Thermos flasks are important utensils in a lot of homes because of how well they maintain the temperature of food items. If you want to heat food, your might be wondering if microwaving it in a thermos is safe.

Can you put a thermos in the microwave? You should not put a thermos in the microwave because it has stainless steel parts that will reflect the microwaves. This can lead to sparks and the microwave oven can get damaged.

According to the Thermos manual, the product should never be placed in a microwave, a conventional oven, or any other source of heat.

Can A Thermos Explode?

A thermos can explode when there is a high amount of pressure built up within the flask itself because of the continuous production of gas. It can also explode if the inner walls are tampered with.

Several things might cause a thermos to explode, but a common source of explosions is pressure buildup. When gasses are compressed in a thermos with limited space, they generate greater pressure on the inner wall of the thermos and lead to an explosion.

However, this gas does not accumulate by itself. It requires a source to generate and gather it to a large volume. This source is usually food or drinks that have been left in the thermos for days. After some time, microorganisms begin to grow to produce gas.

A common gas known to be a result of residual food and drinks is Carbon Dioxide (CO2). When food and drinks ferment for days in a confined space, CO2 is produced and can accumulate to a hazardous amount, exploding when the pressure becomes excessive.

An uncommon reason why a thermos might also explode is a failure in the material of the thermos. The vacuum region contains two flasks that are partially evacuated of air to reduce heat transfer.

However, once the vacuum region is compromised, air pressure begins to form within the thermos and would lead to an explosion if opened suddenly.

To avoid explosions from your thermos, you must be wary of the hours your dishes spend in the flask. Bacteria grow quicker between 40F and 140F, therefore perishable meals should not stay in that temperature range any longer than three hours.

How Do You Heat Up A Thermos?

To heat up a thermos, you need to boil some water and fill your thermos with the boiling water. Then, insert the lid and let the steam heat up the rest of the thermos before pouring out the water.

The good thing about heating up your thermos is that it primes the inner part of the thermos and allows your food to stay warm a lot longer than usual. It also prevents food poisoning by disinfecting any bacteria that might be lingering in your thermos.

You might be wondering how this works, but the scientific secret to a thermos is a vacuum. The double-walled container sucks out the air between both walls to create a vacuum. This process leads to the thermos flask minimizing heat transfer via any medium like conduction, convection, and radiation.

The vacuum in a thermos helps to regulate the temperature of the thermos’ contents by stopping the transfer of heat from the food or drink to the environment.

Therefore, heating up your thermos with hot liquid not only makes the material in the thermos warmer but also pre-heats the air inside the thermos, thereby, maximizing heat retention.

Failure to heat up the inside of your thermos allows the stainless steel wall to strip a certain amount of heat from your meal. Eventually, it makes your dish get colder faster.

There are several steps to heating up a thermos. Some of which are;

●      Boil the water you need to heat your thermos up.

●      Pour some hot water into the thermos.

●      Secure and tighten the lid immediately.

●      Allow the steam to circulate inside the thermos for about 5-10 minutes.

●      After the allotted time, pour out the water.

●      Fill your thermos with the hot dish or beverage of your choice.

Thermos specializes in developing beverage containers that provide maximal insulation performance in any condition.

Unlike past thermoses that broke easily, modern thermoses are made out of plastic layers. Not only do they reduce heat transfer, but they also retain heat. Hence, the reason for the prolonged warmth of food when the thermoses are first heated up.

Best Thermos for Hot Food

Here is a table that highlights what forum users have stated is their top picks for thermos that for hot food. I used forums that were related to survivalism.

Thermos for Hot FoodPercentage of Total Responses
Zojirushi 18%
Stanley 41%
Hydro Flask 17%
data from various survivalism forums

Can You Put A Thermos In The Fridge?

You can put a thermos in the fridge if it contains a liquid that you want to cool. Placing a thermos in a fridge will not damage the thermos but you should ensure that it is not full since some liquids expand when cold.

A thermos has insulators and a vacuum that prevents heat transfer. This vacuum means there is no air between the inner and outer thermos parts. Heat can easily be transferred through the air and since there is no air, heat cannot escape. I recommend the Iron Flask Sports Water Bottle that is available on Amazon. Click to get yours.

This mechanism works the same way for cold liquid. The cold from the contents of the thermos cannot be transferred to the surroundings. The cold liquid retains its original temperature because the heat that might transfer into the liquid from the environment is prevented by the vacuum in the thermos.

Apart from storing cold liquids in a thermos, you can also use the thermos as a regular container. You can put liquid in the thermos, then place it in a fridge. This will help maintain the low temperature of the liquid that you want to cool.

When pouring a liquid into a thermos and placing it in a fridge, you should ensure that the thermos is left open and not covered with its lid. Also, do not fill up the thermos with liquid. When some liquids, such as water, get cold and start to freeze, they begin to expand.

If the thermos is completely filled up with a liquid that begins to expand when freezing, the expansion can cause the thermos to crack and get damaged. Also, if you want to cool a hot liquid by placing it in the fridge, you should ensure that the liquid cools down a bit before refrigeration.

If you put hot substances in the fridge, the temperature difference will cause the formation of condensation which becomes solid ice that will cling to the sides of the freezer.

This frozen condensation can be a nuisance since it will hold onto items in the fridge, causing them to be stuck to the walls. To avoid this, let your hot food or drink cool down to room temperature before refrigeration.

Can You Put A Thermos In The Dishwasher?

You can put some thermos flasks in the dishwasher if they are placed on the top rack. It is better to wash them with your hands, however, as constant dishwashing can affect the lifespan of a thermos.

There are just a few bottles, or flasks that are dishwasher safe. But now, some companies are still producing dishwashers that can clean thermos.

While your “everyday” dishes and glassware are probably dishwasher friendly, that might not be the case for your thermos.

Stainless steel thermos flasks can be safely washed in the top rack of a dishwasher, but hand washing is still your best choice. The combination of detergents and hot water in a dishwasher can affect the vacuum seal of your thermos flask and shorten the lifespan of its insulation.

You should note that glass vacuum thermoses are not dishwasher safe. Glass is a lot more fragile than stainless steel. When a glass thermos is exposed to the heat from a dishwasher, it can lead to the formation of cracks, shortening the lifespan and damaging the vacuum seal.

Most importantly, you should check the manuals or contact the manufacturers of both your thermos and your dishwasher to ensure that they are compatible with each other. Also, you can check out ways to operate your dishwasher that will potentially cause the least amount of damage.

Finally, you should never wash a thermos flask with bleach or bleach-containing products as this can negatively affect the thermos.

Can You Microwave The Thermos Funtainer?

You should not microwave the thermos Funtainer as it is quite unsafe. Putting a thermos Funtainer in your microwave can both damage the microwave and cause a fire.

Microwaves are easy to operate, but they cannot be used with just any item. Eggs, paper bags, grapes, Styrofoam, and hot peppers are among the items that should not be found in a microwave.

Most of these items are incompatible with a microwave because such a combination can lead to a fire, not only damaging the microwave itself but also potentially causing a proper fire in your house. One other item that can also cause a house fire when placed in a microwave is metal.

When metal is placed in a microwave oven, the microwaves emitted by the oven cannot be absorbed by the metal, causing them to dance around the surface of the metal. This can cause sparks, damage the microwave oven, and lead to a fire.

If you own a thermos Funtainer, you might be considering using it in the microwave. However, you shouldn’t, because it can be quite dangerous. Thermos Funtainers have metal parts, making them incompatible for use in a microwave. If you are interested in having your own Funtainer, I recommend the 12 oz Funtainer that is available on Amazon. Click here to have yours delivered to your front door.

Apart from being dangerous, the presence of metal will likely prevent your food from getting properly heated in a microwave. Also, some thermos Funtainers are not supposed to be used with hot liquid, meaning using them to heat liquid in a microwave is inappropriate.

Will Microwaved Soup Stay Warm In My Thermos As Long As Stove-Heated Soup?

Microwaved soup will stay warm in your thermos as long as soup that was heated by a stove. When it comes to how long food stays warm, what matters is not the method that was used to heat it but the storage.

Cooking can be exciting, and even if it isn’t for you, it is an important part of most of our daily activities, as we need food to survive. Over the years, human needs and tastes have evolved drastically, particularly with the rise of technology.

Our interests in the kitchen have also evolved with time, and now, there are tons of cooking methods that can be applied to various foods. The cooking method you choose to adopt can depend on the food type, cooking time, or resources.

Stoves and microwaves are some of the most common cooking methods available to us, with microwaving being the more recently developed of the two. Currently, people cook with different types of stoves, with gas and electricity variants being the most popular.

After cooking food, storage is another important factor. This is particularly important for people who want to eat their food at a different time from when it was cooked, but still want it to retain its original hot temperature.

A thermos flask is a great way to store your heated soup since it will keep the soup warm for a long while. Whether you are heating your soup with a microwave or with a stove, the amount of time that your thermos will keep it warm is the same, as long as the soup was heated to a fixed temperature.

So, your concern when heating food should not be the method that was used to heat it, but rather, the way the food will be stored. Thermos flasks, bowls, and containers are very efficient products, and they can keep your soup hot for over 5 hours.

There are some reasons why your thermos might no longer keep food hot for long, like if the vacuum seal has been damaged. If you are experiencing a drop in your thermos’ efficiency, you might need to purchase a new one.

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Aron Blake

I am the lead copywriter on Homezesty and the Webmaster. I have a lot of experience in home renovations and the creation of style. I enjoy writing and sharing my tips on how to create the best living environment. My Linkedin Profile, My Twitter Account

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