The Sauna 

Well, The Sauna has become known all over the world as a finnish peculiarity. Of course the swedish are trying to convince the people that the Sauna is part of the swedish inheritage. By one quick test all this can be proven false - the finns call a hot, moist room a Sauna while the swedes have their own word for it that is a "bastu". (sounds pretty much like a b'stard when pronounced aloud)

To be honest, it seems that everybody had Saunas all over the world about one millenium ago. Then came the church and denominated it as a sin to be naked in a bathroom with other people. Finland was just too little a country too far away from the Vatican to be of concern and thus the habit was preserved here while it was hounted down everywhere else. However, it is great fun to bath in a sauna, indeed !

The basic idea is to sit quietly in a room, the temperature of which is around +80 C, throw some water on the hot stones of the stove every now and then, lay back, relax and enjoy. Once you feel thoroughly heated up (in 10 minutes or less) go out, enjoy a warm shower and wash all the dirt away with some soap and a sponge. After the heat treatment your skin poroughs are all wide open and the dirt comes easily and completely out. (there are people who prefer over 140 C temperatures but for me it is just too hot, it feels like your back skin would split any moment)

Then comes the fun part. Go back to the heat and throw a bit more water on the stones, as much as you can still comfortably take. Once you are sure that you cannot be there a single second longer, get out and plunge into cool water ( a shower can do if no lakes are handily available). Then get back in and repeat until you feel totally overwhelmed and relaxed. Lay back next to the fire place and have a long sip of a cold beer and get to know what it is like to live in Finland.

There are three principal brands of a Sauna. 

Electric Sauna

Most common version is a small, 2 - 6 m² apartment sauna that is heated up by electricity. Once properly ventilated it is all right if you don't know of better and almost every family has one of these. You better take care that the foot ramp is above the top of the stove, otherwise your feet will feel cold. This type of sauna takes about 45 to 60 minutes to warm up.

This is something we have at our town home basement. Nothing fancy, a bit lack of air but better than average. I made the mistake to believe the sales talk and equipped my sauna with a special stove made of soapstone that was claimed to heat up also the space below the top. It was not the truth but the price was double, of course.

Of course I had to make the difference also here and built up my own design round corner radial cut seats with a rounded front edge, made of tempered aspen. Looks good but it took me over two months to get it done with.

Wood Heated Sauna

This is a bit larger, 6 - 15 m² wood heated sauna that is common on countryside and in detached houses. Because of the wood fire there is enough draft to make it airy and fresh, not to mention the homely smell of the burning wood. While the stove gets hot from foot to top there is no danger that the feet would feel chilly as they unfortunately often do in an electric sauna.

This is the sauna we have at our country house. So far I haven't gone through the effort to rebuild the seats, nor the chimney insulation. The heat is good, smooth and airy, gives you a very nice feeling. This sauna takes about 20 to 30 minutes to heat up - really quick !

Note the plate hanging above the stove, it is for warming up the Finnish sauna sausage !

Check the renovation down below !

Smoke Sauna

This is the crown jewel - The Smoke Sauna !

The floor area is about the same than of the above but the height of the room is remarkably higher. The method of heating up this sauna is rather exceptional, inherited from our ancestors,  thousands of years ago. It is the key to the comfortable heat of this type of sauna. Build it up with no metal inside the stove and you can experience the relaxing feeling of all the negative ions floating around you.

The whole room acts as a chimney during the heating. There is a small opening up at the rear wall for the smoke to get out (the smoke hatch), sometimes assisted by a center pipe, the lower end of which brought low, down to the level of the top of the stove. 

The stove itself is a huge pile of stones, approximately 1 ton of weight. There are as many varieties of the construction as there are smoke saunas. Mine is wrapped in a brick enclosure, having absolutely no metal inside, only bricks, special ceramic balls and stones. It takes about 3 hours to heat up the stones, special for the purpose, called peridotite. Once they are hot enough they start to glow red and that is when you can start to prepare the sauna for bathing.

Peculiarly enough the smoke never falls below the top of the stove but stays in the upper part only. As the picture on right shows, the walls (and everything else) above the stove top are completely black, covered by soot while the lower parts stay rather intact. For this reason the seats have to be either covered or taken down during the heat up period, otherwise sitting on those would be a rather messy business. It should be understood that the bathers must also keep away from the walls and hand rails, not to become unwillingly colored black on parts of skin that even slightly touch the soothed surfaces. On the picture left it becomes obvious that only the upper seats have to be taken down during the heating, the foot plane is low enough not to get soothed even when left in place.

To make it more comfortable to sit on the rather hot seats some sheet are placed on the seats before bathing.

Oh, I almost forgot to mention that our Smoke Sauna is unique !

It is the one and only microprocessor based Smoke Sauna in the universe. Look at the picture of the Smoke Sauna above, it is on the front wall, just underneath the white plastic seat. People keep on asking me what the microprocessor is doing there. That is the beauty of it, it is there to do absolutely nothing at all. Even the microprocessor itself can lay back and relax in our Smoke Sauna ! 

(MC68000 to those that are curious)                       

For those who have more interest into this subject, please visit the home page of  the  international smoke sauna club and select your language.       

Experiences on our Smoke Sauna

So far our Smoke Sauna has been heated up about 70 times in a time period of a bit over three years. Almost biweekly. The chosen principle to make a hole on the wall and heat the stove from outside turned out to be most convenient. Instead of the traditional way to dug into the smoke filled room to add more firewood you can stay in the fresh air and breath normally.

Then I suddenly noticed that there was something wrong with the stove. The hatch felt loose and by closer investigation so did all the firebricks inside. I took out all that 1 ton of stones to give it a closer look. On the right you can see what I saw. The firebrick plaster had been made into muddy water and because of that it never hardened. I could hand pick all the firebricks out of the stove ! We were so lucky not to have the whole sauna burned down because the fire inside had practically free access to the logs of the wall.

So, I emptied all the firebricks inside and hired a proper bricklayer to build it all up again. The hammer in the picture was only needed to remove the bottom layer of bricks that were built up with normal type of plaster that works also on muddy water.

The construction to hold up that 1 ton of stones was also renewed. Instead of the vaulted firebricks that gave in and let some of the stones to drop into the furnace the new construction utilized a new type of molding compound that can handle temperatures up to 1200 C and will not to crack even if thrown into water at that temperature !

When the stove had been drying up for a good week it could be heated up, first very slowly and finally up to 600 C to give it the final strength. First I covered the top nicely with tiles, plastering them down with renovation plaster as instructed by the hardware store expert.

Two days later I started to heat the stove up, first with a gas torch, spending an hour to blow the flame in the stove. First a very small flame and finally at full blast, a 30 cm long blue flame roaring into the empty stove. Nothing happened. The bricks heated up just by nothing.

I placed the 1 ton of stones back to the stove, now paying careful attention to their orientation, not to block the route of the smoke by large horizontal planes but left curved vertical channels between the stones to allow better draft. Then I placed the hatch back -  or that was my intention. It was intended to be screwed in place by four motorcycle spokes that were placed in between the bricks. Unfortunately my proper bricklayer wasn't able to take measures and so one of the spokes was left about 2 cm too short to reach to the hatch. I fixed it with three and asked my colleagues to make me one special long nut to reach to the spoke.

Then I put up a small wood fire into the stove, keeping it going for over two hours, heating up the stones and bricks nice and slow (notice the tilted hatch, lower left corner being not yet fixed in place). During this process I suddenly noticed that the joint between the firebricks and the bar above the hatch made of that molding compound had cracked. Obviously non-matching temperature coefficients ! I started to add heat by putting in more wood, first one third, then half full and finally 3/4 full. Then the stove suddenly started to make noise, banging like rifle fire with the whistling sound of bullets, too ? Some familiar sound of one-arm-bandits was also mixed to this polyphonic concert, like coins rattling onto that metal trough. I had to open the hatch and have a look. I was almost hit by rocketing bits of stone ! The edges of the compound beams were not rounded but sharp and the thermal expansion of the stones created enormous local surface pressures to those, making pieces of the compound to crack off and shoot around the fireplace.

After two and half hours of full heating the stove was ready, all stones (and the molded compound beams) glowing red. Cleaned the stove from still burning pieces of coal and ash  - and about two liters of cracked off pieces of the compound material, size of a fingertip ! Threw some water on the stones to wash out the dirt and ventilate out the CO in the air. After two hours of stabilizing we enjoyed the best ever sauna bath - the heat was so smooth and lasting, air fresher than ever before. Great !

Next morning I inspected the still very warm stove. To my great disappointment all the tiles on top had cracked off, that plaster I was recommended was not good enough for the purpose. The bricklayer had used two brands of firebricks, Finnish and Russian. Every joint between different kind of bricks and between the compound parts and bricks had cracked ! Oh my ;-(

Renovation of our Wood Heated Sauna (October 2009)

Our 10 years aged log house has lowered because of the drying and shrinking of the log walls. Unfortunately the brick built fire wall did not allow the sinking enough and the building was warped, leaning on the fire wall.

To fix this the sauna ceiling had to be torn down, the fire wall had to be hammered down by some 15 cm and then the ceiling had to be just rebuilt back again.

While the renovation process was going to tear the whole sauna decor down I decided to make use of the opportunity and redesign the sauna to better serve its divine purpose.

Originally I had the idea to have two opposite seats and the stove right in between. However, during the ten elapsed years I never managed to figure out how to treat the chimney properly. As you can see at right (and above in the Wood Heated Sauna chapter) the chimney was wrapped in insulating material and just making its way through the room, looking terrible and blocking almost half of the left hand seat.

Once the whole sauna was rebuilt I asked the carpenters to move the stove to the corner, lead the chimney directly up to its joint and put a plate of insulating mineral material to the ceiling in order to get rid of the drooping pipe insulations. At left the result is shown. The pipes did not fit, I was told.

Well, at right is the proof that by cutting and reorganizing the pipes they surprisingly did fit ! Had to do it by myself - again.

There the stove is heated up for the first time, really hot for two hours and without stones to burn off the storage grease. All windows open of course. Pay attention to the hatch - transparent to see the flames, it really made the atmosphere warmer :)

Well, that reorganization made the chimney look good but asked for a complete rearrangement of the seats. Two opposite seats were now out of question - or were they ?

I spent some time to rethink the whole concept. Decided to make it something different  - for a change ;-)

I  built a lifted up floor to the heat room, above the stove top surface to keep all the body parts for sure in the hot air. Of course I had to make part of the floor as a lid that could be lifted up for an easy access to the stove to add wood in it. The hinges show at right.

The main seat is at the right hand side, providing room for 5 to 6 bathers. Rounded seat corner with radial cut seat of course. At left is a special seat reserved for a single person responsible of controlling the heat by throwing proper amounts of water on the stones.

The hand rail there is still seeking for its final shape.

During the years I have become a some sort of an expert in the sauna stove stones. To get a nice, slow, smooth heat wave when water is thrown on the stones it is essential to utilize the right kind and size of stone. That is the key element of a good sauna. The stone must relinquish its heat slowly, not by a sudden burst.

I tried to find special deep stone called peridodite, a mixture of olivine and hornglow with some pyroxines in it. Even better to find dunite that is pure olivine. Unfortunately I could not locate these special minerals but had to satisfy myself to a mid-deep stone called olivine-diabase that is the most commonly achievable sauna stone in Finnish hardware stores.

I purchased 46 kg of stones, washed and sorted them out carefully. Placed the biggest ones to the stove bottom, tightly next to each other, using the smaller size the higher up I got. Overfilled the stove by 20 %.

The effort was worth of it ! The heat is delivered nice and slow, making the feeling almost as good as in the Smoke Sauna - but just almost. The best thing is that after you had the sauna bath, you can go there again after half of an hour and redo it - the stones still have heat enough in them to go for another round !

That handrail was a disaster. Tried to make the top plank tilted by 30 degrees having 45 degree angles horizontally. Close but no cigar ! Not satisfied to what I see.

I also disliked the stupid small edged mineral plate above the stove - with the back wall wooden list still entering the hot area !

Time for a redesign. Starting from the ceiling I renovated the insulation. Once I got used to the mineral material I made it round and nice - and added the side burns ;-)

Next I will make the handrail and mid-floor edge similarly rounded as well.

To be continued...