Many will tell you that it’s not a good idea to put hot drinks in a glass container, but I don’t agree. I have poured hot liquid into glass mugs with success many times. You just have to be careful.
Being careful is really important when pouring something hot into something made of glass. This is because glass can shatter when you pour hot liquid into it and this can be very dangerous. All I am saying is that it is possible to enjoy a cup of joe in glass cups or any kind of glass container for that matter (at your own risk).
Here is a list of glass containers that might not be perfect for hot beverages:
- A mason jar or any other glass jar
- A wine glass
- A glass pitcher
- A water glass
Okay, so the short answer is that if you pour hot coffee or even hot tea or hot chocolate into a glass that is merely room temperature, the high heat could very likely crack the glass. However, there are things that you can do to try and prevent this. If you want to skip the part about why the glass cracks, you can go to the section about different ways to prevent the glass from shattering.
Can You Put Hot Coffee in Glass Containers?
We have to face it that ordinary glass is not made for hot beverages. There is no denying that. The high temperatures of hot water bring about a sudden change in the temperature of the glass to crack.
Thermal shock occurs when the glass has a high thermal expansion coefficient. This means that the glass will heat up unevenly due to bad thermal energy conduction. This leaves the glass susceptible to cracking because the bonds between the molecules weaken when it is heated.
When it comes to pouring hot coffee into glass, the inner layer of the glass heats up faster than the outer parts.
The best way to avoid sudden temperature changes to cause shattered glass is to use heat-resistant glasses.
What is Heat-Resistant Glass?
Heat-resistant glass is glass that has been tempered. These glasses have a very low thermal expansion coefficient, which is just a fancy way of talking about how much something expands when it is heated. If something has a low thermal expansion coefficient, it is less likely to shatter when it is suddenly brought into contact with something hotter than it.
Borosilicate glasses are glasses that have been treated to withstand sudden temperature changes. This is because it contains boron trioxide. So, you can pour liquid of a higher temperature into it with ease of mind, because the temperature difference won’t cause your precious morning coffee to be spilled all over your kitchen counter.
How to Know If a Glass is Heat-Resistant?
Heat-resistant glasses usually have a sticker or some other kind of marking on them to tell you that it is safe to use with hot substances. If there is nothing, it is safer to assume that they are not tempered.
How to Pour Hot Coffee Into a Glass
Now that we know which glass is made to be safe for hot drinks and which is not, we can look at how to fill these containers with hot substances. These methods do not only apply to glass that has not been tempered. I also use it when I work with glass that is marked as heat-resistant to be on the safe side.
Here are the steps for pouring hot coffee into a glass:
- Make sure that the temperature of the glass is at least room temperature
- If the glass is not warm enough, slowly heat it by placing it in water that is not too hot
- Slowly pour a bit of the coffee into the glass (about 1cm/0.4”)
- Swirl the coffee around in the glass so it can warm it up
- Slowly pour the rest of the coffee in
- Don’t stir too aggressively
The Best Cup Materials
Despite all of the above the best material for a reusable cup that you put your coffee in are:
- Stainless steel mugs
- Ceramic mugs
- Tempered glass
- A plastic tumbler or cup
There are of course disposable cups that can do the same job, but with more harm to the environment, which is why it is not on my “best material list”. Rather get yourself a travel mug, but either way, here is a list of these containers:
- A styrofoam cup
- A single-use plastic cup
- Paper cups
Drinking your coffee from a heat-resistant container will always be the best option. But sometimes we coffee lovers want to use something a bit fancier and this is where the above tips come in. I guess I should put a “don’t do this at home” sticker on this article, but the point of it was that you will probably try it.
So my advice is to be safe and careful. You don’t want to burn yourself.
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