Guest post series continues. Welcome Dick from Scandia, Minnesota. Dick works in Research and Development at the Andersen Corporation (Windows) He has worked in Design, Project Management and Materials Research for 33 years.
7 things you may want to know about your sauna stones
You can collect your own “rocks.”
“The best choice for sauna rocks are the ones closest to home that are of suitable composition.”
If you are still with me I know you probably have a wood burning sauna. Someone who would wonder about collecting their own sauna rocks would probably burn wood. There is a certain person who cuts wood and dry’s it, carefully splitting and stacking it in preparation for taking sauna- It’s the “Gestalt” Principle, in action! The preparation is just as important as the Sauna and when combined together give us an exhilarating experience. That same person is likely also to search out and find their own “Sauna Stones” enriching your experience further.
(Or you may just be a good Swede like me and you’re too cheap to lay out your hard earned cash for a pile of rocks…)
If you are wondering why I switched back and forth from rocks to stones I think of them as rocks when they are in the wild and they become “Stones” once they are placed in my sauna heater.
A word of caution!. Gathering stones for your sauna is not the same as Rock collecting. Everyone grabs a pretty agate from the restaurant landscaping or even at a city park. Taking an entire 5 gallon pail of rocks from public beaches, parks and private places is not alright. Take a care and only collect rocks with permission or from land you own. You might want to try a local landscape company or nursery supply business. Mine lets me even sort through the pile and pick just the “Perfect” ones.
“All men are created equal; but no place more than in sauna.”
— Author Unknown
Importance of Stones
The stones deliver the steam. Stone size density, porosity, and surface all play a role in transferring heat from the fire to you. If we use too small of stone it doesn’t hold enough heat to last very long. Too large and it takes longer to heat up. A stone with a nice rough fracture is nice because it has a little more surface area to hold on to the water and gives off more heat. Some stones might stack too close together and prevent the free flow of heat and water through the pile. Too loose and too much water passes through too quickly.
I use stones about the size of my fist with a few larger and smaller to fit just right when I lay them in my stove.
Note that folks with those new fangled electric stoves need to be careful about their stones because stone size and placement can shorten the life of the elements…
READ your instructions warnings!
Black Rocks Matter.
I had to shamelessly say it. Now that I’ve got that out of the way let’s move on.
Darker rocks give off heat quicker. It’s a physics thing. The “Finnish” stones for sale are all dark.
Look up Absorbtivity, Emissivity, Reflectivity, Transmissivity,
T=(αϵAAcϕσ)1/4T=(αϵAAcϕσ)1/4 and AcAc: Ein=Acαϕ
(If you want to know more… I say “Nerd”.)
Types of stove stones: (structural integrity)
Sedimentary- Metamorphic – Igneous, Oh my!
I noticed some companies tend to say things like “the only correct stones”, “the only real sauna rock” or “the correct type”…These are written by “Ad men” and are simply trying to convince you that they have the very best rock for your money. Now be assured, proper sauna rocks are a safety concern. But any igneous, structurally sound rock will work in a sauna and you will be hard pressed to appreciate the differences unless you are 100% Finnish.
Without getting into a geology class let’s just say if you can scratch material off the rock with a nail, DO NOT USE IT!.
Sedimentary rocks (sandstone, shale, limestone, etc) and Metamorphic rocks (slate, marble, Quartzite, etc…) all are too soft, have faults in them or have moisture in them and should not be used. These rocks with moisture in them can “POP” when subject to heat…
We want an igneous rock (Vulcanite, gabro, peridotite, Basalt, Olivine, Granite, etc…) Note I did not include Obsidian and Pumice, both bonafide igneous rocks but they have issues. Obsidian is so smooth that the water will run off so quick it will not have time to evaporate much. Pumice is so light and porous that it will cool too quick and not have enough mass to give you the sustained heat a sauna needs.
If you are having trouble identifying your rocks. Do an internet search for igneous rocks and that should help you. You can also search for a map of your area showing what the predominant rock type is in the area. Some folks might have to wait until vacation to find suitable rocks and depending on who’s with you… you might have to only bring a bucket full at a time home.
Loading of Sauna Rocks-Stone can be dirty.
Before loading your stones in the Rock Chamber, wash and rinse them to get off anything that might soil your floor or impart an off Oder when heated. Next depending on your heater, start with the largest stones first and then use smaller and smaller, stack them in and around the Rock Chamber until it’s full and heaping. You do not want them so tight that air has a hard time getting through but you want them close enough that when you pour water on, it doesn’t run quickly off and doesn’t have a chance to turn to steam.
Some rocks will last longer than others. I’ve heard that some only last less than a year. Whoa! Those are not rocks we want to use… But after a while rocks will crack and get smaller and smaller. Usually the hottest rocks next to the fire pot degrade first. They are subject to more thermal expansion due to the heat / cold cycle. You might want to use room temperature water rather than cold to limit this stress on the rocks and also use only a cup of water at a time to limit the stress also. It’s better to dump a cup on a few minutes apart than 2 cups all at once…
When your rocks are cracked and getting small, some are ending up on the floor. It’s time to replace them. Simply remove them all and combine the old useable good ones with your new rocks. . . See #3 above.
The Spiritual Side
“A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral sauna.”
“We often throw rocks not realizing that they’re going to land somewhere.”
― Craig D. Lounsbrough
(Few people know she was also thinking about her sauna)
“I’m allergic to rocks hitting me in the face.”
(Never throw rocks in your sauna)
― Mike Rowe
I will conclude with this great quote from Constance Malleson from her book, “In the North: Autobiographical Fragments of Norway, Sweden, Finland: 1936-1946.”
“The sauna… Is an apotheosis of all experience: Purgatory and paradise; earth and fire; fire and water; sin and forgiveness. It is lyrical ecstasy. It is resurrection from the dead. It is eternal new birth… You are healed, you are made new.”
PS- Here’s a fun thing to do. When you are at a Chinese restaurant and you get a fortune cookie. Always add “In a Sauna” to the end of you fortune. It makes them much-more-funner…