Although infrared saunas are experiencing a surge in popularity (and rightfully so, given their wealth of benefits), there’s another type of sauna that’s been around for millennia: The dry sauna, also known as the Finnish sauna.
The hallmark of a Finnish sauna is its sauna stones, which serve to do two things:
- Absorb and retain heat.
- Produce steam.
But what exactly are sauna stones and how do they work? Keep reading to find out.
What Is a Finnish Sauna?
Finnish saunas originated many thousands of years ago and are still widely used by Finnish people.
In fact, according to an article titled “Bare facts of the sauna in Finland” published on ThisisFinland, the country has an estimated 2 million saunas for a population of just over five million.
A Finnish sauna is composed of a stove (either wood-burning or electric) topped with a basket of rocks, all housed within a small wooden room. If the stove is wood-burning, it may be equipped with a chimney, although the most traditional ones are not.
Thanks to their many physical and psychological benefits , Finnish saunas, and saunas in general, have gained popularity in many non-Scandinavian countries, including the U.S.
Finnish saunas are also commonly referred to as dry saunas because they utilize the dry heat of burning wood. By contrast, wet saunas (also known as steam rooms) utilize the humid heat of steam.
What Are Sauna Stones? How Do They Work?
As mentioned above, sauna stones are rocks that are placed in a basket above the sauna’s stove.
Although some companies sell sauna stones, you can gather stones from your own property and experience the same results (see below to find out how to select good sauna stones).
Sauna stones have two major functions:
- Absorb and retain heat.
- Produce steam.
Since they’re thermally conductive, sauna stones will accomplish the first of those two functions simply by sitting in the sauna. This is because sauna stones are thermally conductive, meaning that they absorb and retain heat.
As they slowly release that heat back into the air, they serve to keep your sauna nice and toasty.
To complete their second function of producing steam, sauna stones need to come into contact with water. This can be accomplished by ladling water onto the rocks periodically — most dry sauna users keep a bucket and ladle in their sauna for this very purpose.
Although pouring water on your sauna stones will create steam, the humidity of your sauna will rarely rise above 10 percent.
The purpose of creating steam in a dry sauna is to encourage sweating and boost your body’s perception of heat, not to fill the entire room with steam.
While it’s certainly convenient to purchase sauna stones from a store, it’s also easy (and free) to collect sauna stones yourself.
You can gather your stones from your own property, or you can ask local nurseries and landscaping businesses if you can take their spare stones.
Whether you’re purchasing or gathering your sauna stones, always be sure to select stones that are:
- Igneous: Hard, non-porous rocks like granite (officially known as igneous rocks) have fantastic heat-retaining abilities. Be sure to ones with no cracks or crevices — porous or cracked rocks can pop or even explode once water is heated inside them.
- Dark: The lighter and brighter the stone, the more light it will reflect, and the less heat it will retain. Similarly, the darker and duller the stone, the less light it will reflect and the more heat it will retain.
- Medium in size: If your sauna stones are too small, they won’t be able to retain much heat. If they’re too large, though, they’ll take a long time to heat up. To avoid those issues, choose medium-sized rocks which are about the size of a baseball or your fist.
- Rough: If you use sauna stones that are very smooth, the water you pour on them will simply slip off before it gets a chance to heat up and produce an adequate amount of steam. So, select rocks with a rough texture that water can cling to.
With this knowledge in your toolbox, you’ll be able to select the best sauna stones possible, enjoy a wonderfully heated sauna and partake in a tradition that dates back thousands of years.