The traditional sauna
Culture and History of the Finnish sauna
u/CatVideoBoye/ wrote a very nice description of the Finnish sauna culture and is also touching on the history of sauna. It is a good read and gives you insight into the tradition. You can find the original post here, or you can read the slightly shortened version below.
What's a sauna?
Like most of you already know the word sauna comes from Finnish. We have had saunas here for thousands of years and according to wikipedia, the oldest are from around 1500-900 BC. It was an important building and in the old days people have even given birth in saunas, as late as the first half of the 1900s. Probably since it was a nice separate building with access to warm water. In 2020 Finnish sauna was added to UNESCO’s Cultural Heritage List. Check the link out for more interesting information but I want to again highlight that. It really shows how important it is in our culture.
Nowadays pretty much everyone in Finland has access to a sauna of some sort. Houses have them, many apartments, like mine, have one and apartment buildings can have a common sauna where you can rent your private hour and they can have a certain period during which anyone can just go there. And of course summer cottages have a sauna and the ones next to a lake are kind of the perfect image of a Finnish sauna. Plus all the public saunas in swimming halls, gyms, hotels etc. Temperature in a sauna can vary but usually it's between 80-120 °C (176-248 F). Mine is oddly low at 60°C but that is because the ceramic stones that I now use really change the way the löyly (water thrown on the stones on the heater to generate steam) hits you. It is softer and accumulates well instead of being kind of short burst of heat that dissipates quickly. I've tried at 80 and I was out of there really quick unlike with more common stones. One reason why staring at a thermometer doesn't make sense. Just try it and see what feels good. And you other Finns, that 60 really sounds low but I tell you, I'm getting out of there after I guess something like 10-15 minutes with red skin so it really works.
Wood or electric? Both work. Wood heated ones are usually considered to be the best. You get a nicer löyly there but they aren't really an option in an apartment house. An electric heater that has a lot of stones can actually give a very similar löyly. I just experienced one that I believe had 500 kg of stone. Same with a small electric heater (20 kg) with the ceramic stones. All of those options are great for a sauna. As long as there are proper stones and you can freely throw water to get the löyly you want. Löyly is the essential thing here. Without it, you can't really call it a Finnish sauna and that is why Finns do not really consider IR boxes to be saunas. This ties to one of the topics often argued: do you need a drain? Yes you do. Not necessarily inside the sauna if you have the bathroom outside. Mine has only a shower drain but the sauna floor is tilted so that any water flows directly there. It's also good for washing the sauna.
Bench heights are often discussed here but why does it matter? Because heat rises. The lower part of a sauna is cold and you want to get your head close to the ceiling and your feet high enough to not feel cold. The "feet at the stone level" is just a nice helper for a basic heater. For tower shaped ones you probably want to find out the exact height. This is also why you need to have proper air flow in the sauna. You want the hot air and fresh air mixed, you want the moisture to leave after you're done and you don't want the heat escaping due to wrongly implemented ventilation. Don't ask me about construction things, I don't know anything about that. I just know mine was built according to Finnish standards and my apartment won't rot if I use it.
What we do in a sauna?
For me sauna is a place to wash since I don't often take a shower without heating the sauna. Yep, I heat it up often. It's also a place to relax and to socialize. I sometimes have friends visiting and we heat it up, chat in there and have a beer on the balcony. It's a place where you can forget about your phone, social media and all that and just focus on your thoughts, happy or sad, or have deep discussions with your friends. There is something about the atmosphere that makes people open up in a sauna and talk about more private things. I know I'm not the only one. I've heard many people say that sauna is the place where they talk about the deep stuff with friends.
The idea of maxing health benefits, that have been found in recent studies, is just not something we Finns really understand. Why? Because we've been to saunas for many other reasons throughout our lives. It's so integral part of my everyday life that making it a spa treatment or some healthy excercise just doesn't fit my understanding of saunas. But if you want to pursue those health benefits, a high enough heat and a strong enough löyly is what you want because that is how we have gone to saunas and gained the benefits that were seen in the studies. Do you need to measure your heart beat and have exact temperature? No. You'll feel your heart bumping and you'll feel the need to get out sooner or later. Staring at heart beat or timers takes away from one of the important points: just sit and relax and let your mind wonder. Löyly transfers additional heat from the boiling water to your body and gets your heart beating fast. That's also good to remember if you actually hunt for health benefits. Sitting in a luke warm cabin with no löyly for a certain time is definitely not the same thing that gave Finns health benefits.
Saunalike concepts in other cultures and countries
Sure, there are similar things in many other cultures. They are not inferior to sauna, they are just a different thing. They have their own cultural backgrounds and reasons to exist. "This is not a sauna." is what you often see written here but that is not meant as an insult that your heated cabin sucks. It just means that we Finns do not really appreciate it if the thing in question is called a sauna, because it does not meet the definition of what we have considered a sauna for thousands of years. Finland is a rather remote and small/unknown country and one of the things people know about us is sauna. That is why many of us would like to keep the image of sauna as correct and original as possible.
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I've got a Kuuma, and the smoke sounds similar to your Egg. Light whispy white smoke when I'm starting it, but once it's going (after 15-20 minutes) the exhaust out of the chimney is basically clear. When I add wood or stoke it, it'll be a little white for a few minutes before settling back down.