If you’ve ever been in a sauna, obviously, you’d know they get very hot. So hot, in fact, that they’re close to water’s boiling point, if not hotter! If this is the case, why don’t saunas burn you when you’re in them?
Saunas don’t burn you because the short duration of 15-20 minutes that you spend inside is insufficient to transfer enough heat from the air or wood to your body to cause burns, even if you touch the wood. Longer durations and other conditions can cause burns.
There are definitely ways in the sauna that you can get burnt. I’ll cover all of those as well as dive deeper into why you don’t burn, down below.
Why You Don’t Burn in the Sauna
When you touch a wooden surface, such as a sauna bench, you might be wondering why you don’t get burned, even though the wood is hot. The reason is not only the heat transfer between the wood and your skin but rather the heat flowing within the wood.
When you touch the surface, the thin layer of wood at the surface and your skin equalize their temperature, but not much heat is transferred because the wood has low heat conductance. The small amount of heat that is transferred is quickly transported away from the skin into the body, thanks to the high thermal conductance of the human body, which includes blood flow carrying heat away.
To further heat up your skin, heat from the center of the wood needs to get to the surface, so it can be transferred to your skin. This process is slow due to the low heat conductance of wood, allowing the skin to transport energy away quicker than it can come from the bulk to the surface, which is why you don’t get burned.
In contrast, touching a metal surface can quickly burn your skin because the heat stored deep in the bulk of the material can rush to the surface rather quickly if something cool is touching the surface. Much more heat is transferred from the metal to your skin, causing burns.
The low heat capacity of a wooden bench also plays a role because there’s little heat stored in the material, which means it has less energy to heat up your skin with. Overall, the combination of low heat conductance and low heat capacity makes wood a safer material to touch than metal.
You Can Burn From Sauna Temperatures
As you now know, you don’t burn in the sauna because you’re only in there for a few minutes. However, if you’re inside for longer you definitely can burn.
There are many examples from Finland, Russia, and all over the world where people are either in sauna competitions, or pass out inside from drinking, and develop severe burns or even die.
If you’re in the sauna for too long, your body won’t be able to transfer in any more heat and still keep cool. This is a very dangerous situation, but unless you’re crazy or intoxicated, you’ll be uncomfortable and leave the sauna long before this becomes a problem.
To avoid any problems here, listen to your body. When you start to feel off, uncomfortable, dizzy, or just too hot, it’s time to get out.
If this happens but you’re not satisfied yet, you can get out, cool down, and get some water before getting back in for another session!
Your Sweat Cools You Down
Another reason that you don’t burn in the sauna is that your sweat is cooling you down. As sweat makes it to the surface of your skin, it evaporates and takes some of the heat from your body away with it.
As the sweat evaporates, your body releases even more sweat and the process continues. Eventually, you’ll run out of water available to produce sweat and you’ll stop enjoying the cooling benefits.
However, you should be out of the sauna long before this point. There’s also the possibility that you struggle to sweat in the sauna, and I wrote an article all about that!
At the end of the day, sweating is a major reason why you’re able to stay cool in the sauna, and one of the main drivers of saunas’ benefits.
Some Things in a Sauna Can Burn You
Other than staying in the sauna too long, there are some things that can burn you even if you’re only inside for a few minutes. Some of these things include:
- Jewelry
- Nails in wood
- Sauna heater/stove
- Anything else metal
As I mentioned earlier, metal is a much better conductor of heat, so touching it in the sauna will likely burn you.
The wood bench of your sauna may have exposed nails. If it’s built right, you won’t be able to accidentally touch them, but the chance is still there.
Jewelry is also a big cause of sauna burns. When you first get in, your jewelry will be at a normal temperature, but it will quickly become hot enough to burn your skin. Make sure you leave the jewelry off before getting in the sauna!
As a personal note, I’ve been in the sauna before and grabbed my locker keys, just to burn my fingers. Metal gets hot in the sauna!
Obviously, the sauna heater or stove will be hot enough to burn you, but I shouldn’t have to tell you not to touch a hot stove.
All in all, if you don’t stay in the sauna too long and you can avoid touching metal, you should have almost no risk of burning yourself.