Finnish saunas have hot stones to store heat and turn water into steam. The heater warms the room and stones; adding water to the hot stones produces the burst of steam called löyly. The Finnish Sauna Society explains the heater's role, while UNESCO describes löyly as central to the sauna experience.
The heater warms the stones
Wood and electricity are common sources of sauna heat. In an electric heater, heating elements sit between or around the stones.
Different designs handle that heat differently. A heat-storing heater is warmed before bathing and holds enough energy in its stones for the session. A continuously heated model can keep receiving heat while people bathe. Both arrangements exist in wood-burning and electric heaters. The Sauna Society's heater guide explains these designs.
The type of stone matters, too. Harvia explains that the density of olivine diabase, one rock used for sauna stones, helps it store and release heat. The manufacturer also tells owners to use the stone size and quantity specified in their heater's manual.
What löyly means
When UNESCO added Finnish sauna culture to its Representative List in 2020, it put löyly at the centre of its description. The entry explains that sauna traditions commonly pass through families.
The ladle is part of a shared experience, so consider the other bathers before adding water. Visit Finland's beginner guide says there is no fixed interval for another ladle: the people sharing the sauna should be comfortable with it.
Before you take a seat
Read the venue's instructions or ask the host how that particular heater is used. Visit Finland's cottage guide points guests to the supplied stove instructions and their host if they need help. Follow those directions before adding water.
Hot steam deserves care. At its Vaskiniemi saunas, the Finnish Sauna Society warns bathers against leaning towards the heater when adding water because the steam can burn. Its instructions describe its own heaters, so ask staff to show you the procedure at the sauna you visit.
For a cottage sauna, Visit Finland advises using a towel to sit on; some cottages supply disposable seat covers. Check what your host provides before packing a separate seat towel.
A towel for the sauna bench
If you want a separate towel to sit on, compare sauna seat towels. Check what your host provides first; a towel you already own may do the job.
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