Coffee mugs are designed to handle high temperatures. After all, they’re made specifically to consume hot beverages. However, that does not mean that their heat tolerance is unlimited and at some point, they will break. Most coffee mugs can be used in the microwave and dishwasher, but are coffee mugs oven safe?
Coffee mugs made from ceramic, borosilicate glass, metal, and silicone are considered oven safe. However, you should still avoid rapid temperature changes to prevent the mugs from breaking.
This article will cover the different materials that mugs can be made from and whether or not each of them is considered oven safe. Then you will learn about what you can do to prevent thermal shock no matter what kind of mug you are using.
Some coffee mugs can go in the oven safely while others cannot. Whether or not they are safe to go in the oven will depend on what material the mug is made from and what coating was used to seal it if it’s made from a porous material.
It is also important to consider what you are placing in your mug before putting it in the oven. Your mug may have a different reaction to the heat when it is full of liquid or food than when it is empty.
Temperature change is the biggest issue that you will have to deal with when you put coffee mugs in the oven. You will want to make sure that your coffee mug does not change temperature too quickly or it could break when the temperature changes.
How do you know if a mug is oven safe?
To check if your mug is oven safe you will want to read the warning that is typically printed on the bottom of the mug. This warning will usually say whether or not the mug is dishwasher, microwave, oven, etc. safe and give instructions on what temperatures the mug can handle.
If your mug does not have this warning label, the best way to figure out if the mug is oven-safe is by checking what material the mug is made from. Some materials are safe to use in the oven whereas others cannot handle the heat and may break or leach chemicals when exposed to high heat.
The main types of materials used for coffee mugs are:
- Ceramics
- Borosilicate glass
- Bone china
- Metal and stainless steel
- Silicon
To learn more about whether or not each of these materials can be used in the oven, read on.
Ceramics
Ceramics are generally considered safe to use in the oven and this is in part because of their manufacturing process. When ceramics are being made, they go through a firing process. This is what seals the ceramics and makes them safe to use and long-lasting. During this firing process, they will reach extremely high temperatures in an oven.
Since they can handle those temperatures, they are able to handle the temperatures in your home oven. However, the exact temperature that your ceramic coffee mug can handle will depend on the type of ceramic that your mug is made from.
There are three main types of ceramic: earthenware, porcelain, and stoneware. The difference between these types of ceramic is in the quality of the clay that is used to make them.
Earthenware is made from the cheapest clay and is the least heat resistant and most prone to breakage. Stoneware is your middle of the road ceramic and is relatively heat resistant and difficult to break. The highest quality ceramic is porcelain. Porcelain is made from the highest quality clay and is the least prone to breakage and heat damage.
What Temperature Can It Handle?
Even though ceramic does have a breaking point under heat, it is likely not a temperature that you will be achieved in any home oven.
The highest temperature that earthenware can handle is 1945 degrees Fahrenheit.
The highest temperature that stoneware can handle is 2382 degrees Fahrenheit.
Porcelain can handle temperatures of over 2300 degrees Fahrenheit.
Borosilicate Glass
Another common material that coffee mugs are made from is borosilicate glass. This type of glass is different from regular glass because it is able to handle significantly higher temperature fluctuations without breaking.
Regular glass is notorious for breaking with temperature changes. That is why you are never supposed to pour boiling liquid into a room temperature or colder jar. The rapid change in temperature will cause the glass to shatter. If you want to use regular glass to hold hot liquids or foods you’ll need to heat it up gradually with the liquid or food.
Borosilicate glass is made by adding boron trioxide to the regular glass mixture. This creates a glass that is much more heat resistant than regular glass. However, it is more vulnerable to physical damage.
This is an important factor to keep in mind because, if you decide to use a borosilicate glass coffee mug in your oven you will want to be very careful when removing it and placing it in the oven. Otherwise, you could end up with shattered glass for reasons other than temperature.
What Temperature Can It Handle?
Borosilicate glass can typically handle temperature fluctuations of about 297 degrees Fahrenheit.
As long as you give the glass enough time to heat up and don’t start the glass off at freezing temperatures, it should be safe to use in the oven.
Bone China
Bone china is another type of ceramic that is very similar to porcelain. However, unlike the ceramics previously mentioned, bone china uses bone ash as one of its ingredients. This bone ash allows the ceramic to be stronger than porcelain and less likely to break.
Like porcelain, bone china undergoes a high temperature in its manufacturing process. This seals the china and makes it safe to use for foods and drinks.
This means that bone china will not break under high temperatures. However, there is a catch. Most bone china dishes are extremely thin and intricate. Even though the material itself is safe to use at high temperatures, the design of the mugs makes them so delicate that bone china is generally not safe to use in an oven.
Metal and Stainless Steel
Both metal and stainless steel coffee mugs are safe to use in the oven no matter what temperature you use them at. Unlike glass mugs, they are not prone to breaking from the temperature change and generally heat up and cool down very well.
Before you place your metal coffee mug in the oven make sure to check if any decorative materials are oven safe. This could include any ceramic trim or paint that is used to decorate the mug. If you place a metal mug that has extra decorative materials on it in the oven you could be dealing with breakage or melting.
To learn more about what types of metal cookware can go in the oven and what temperatures they can handle, click here.
Silicone
The last material that your mug may be made from is silicone. Generally speaking, silicone cookware is safe to use at high temperatures and will not crack from thermal shock.
Just like with the metal mugs, you will want to make sure that any decorative materials are also oven safe. You don’t want any paint or plastic to end up melting off your mug.
Why Coffee Mugs Crack After Baking
The reason that coffee mugs crack after baking is because of something called thermal shock. This occurs when there is a rapid temperature change. This can cause the outer layers of the mug to heat up rapidly while the inner layers stay cool.
This variance in the temperature can cause swelling and contracting which will lead to stress fractures. Over time these stress fractures may extend and turn into real cracks or even shatter the mug.
The best way to avoid your mug cracking after baking is by making sure that you protect the mug from rapid temperature changes. You can do this by heating the mug up with the oven and by letting the mug cool down in the oven after baking. That way the temperature changes are not as significant.
How To Avoid Thermal Shock When Putting A Coffee Mug In The Oven
To prevent your coffee mug from breaking when putting it in the oven, you should make sure to avoid thermal shock. Thermal shock occurs when there is a rapid temperature change and the mug cannot heat evenly.
To avoid thermal shock you should know the maximum temperature of your dish, let dishes rest on the counter, avoid moving from the freezer to the oven, and don’t expose regular dishes to direct heat.
Know the maximum temperature for your dish
The first thing to do to avoid thermal shock is to make sure you know the maximum temperature for your dish. If your dish is made from ceramic, make sure to not heat your dish above the maximum temperature for that type of ceramic. Heating up a material beyond its safe temperature point is a surefire way to create thermal shock.
Let dishes rest on the counter
The second way to avoid thermal shock is by making sure you let your dishes rest on the counter before and after heating them up. This will allow the mug to come to room temperature gradually. This is especially important if the mug was in the fridge or freezer prior to heating.
Don’t move cups from the freezer to the oven
The most important thing to avoid when you’re trying to prevent thermal shock is moving cups from the freezer to the oven. When you move cups directly from the freezer to the oven you are exposing them to a temperature change of more than 300 degrees Fahrenheit on average. This rapid temperature change can easily cause fractures in many materials.
Don’t expose normal dishes to direct heat
The last way to prevent thermal shock is by only using dishes that are safe to use in the oven. Normal dishes are not heat treated which means that they could break or melt at high temperatures.
Make sure that you only use oven-safe dishes in the oven. If you are not sure if your dish is oven-safe it is better to be safe than sorry and not use the dish.
Oven Unsafe Cups
Although many coffee cups are safe to use in the oven, some should never be used in the oven. These include coffee mugs made from plastic, paper, and melamine.
Plastic
Cups that are made from plastic should not be used in the oven. When exposed to high temperatures, plastic tends to melt which will release toxic fumes and could ruin your oven.
Some plastic is safe to use in the microwave and dishwasher, but it should never be used in the oven.
Paper
Another material that should never be used in the oven is paper. Paper will catch on fire in the oven which could create a house fire or, at the very least, permanently damage your oven.
Melamine
The last material that you should avoid is melamine. Melamine is a synthetic material that is often used in kitchenware. However, it should not be exposed to heat above 180 degrees Fahrenheit so it should never be used in the oven.
Conclusion
Coffee mugs are frequently used to hold hot liquids. However, this does not mean that they are always safe to use in the oven. Depending on the material used to make the mug, your coffee mug may or may not be safe to use in the oven.
Coffee mugs that are made from ceramic, silicone, metal, or borosilicate glass are generally safe to use in the oven. Mugs that are made from plastic, paper, or melamine are not safe and should never be used to prevent fires and melting.
No matter what material you use, you should always avoid rapid temperature changes which can cause thermal shock.
