rocks [ recall ] are an integral component of sauna. without rocks, there is no löyly and, without löyly, there is no sauna.
the selection of sauna rocks, therefore, becomes a critical aspect. a choice that directly affects the quality of löyly and, by extension, the sauna experience
selecting your rocks
selecting appropriate rocks involves consideration of various properties. these properties include heat capacity, density, and resistance to thermal shock
igneous rocks, formed from cooled magma or lava, excel in these aspects. igneous rocks include those like peridotite, olivine, vulcanite, especially well-suited for sauna use, granite
granite
granite is a type of igneous rock commonly used in saunas. it has high heat retention properties and withstands thermal shock, making it an ideal choice for enduring the sauna’s intense heat
unlike sedimentary and highly metamorphic rocks, granite does not absorb water readily. this ensures it does not burst or crack when heated, providing safety and longevity
granite is also widely available, making it a practical and affordable option for many sauna owners
rocks to avoid
steer clear from sedimentary rocks like limestone or sandstone. these rocks are softer, absorb water, and can crack under high heat
in a similar vein, highly metamorphic rocks like quartzite should be avoided. these stones can hold water in their layers and can burst when heated
the cracking – in both the splitting apart and, especially, the explosive noise senses of the the word – of wet rocks, freshly collected from a lakeshore and rapidly heated, is terrifying
rock size
the size of sauna rocks matters too. opt for rocks that are roughly the size of a fist. this size ensures better heat distribution and prolongs heating periods
these are the fundamentals to consider when selecting rocks for your sauna. in making an informed choice, you can enhance the sauna experience, ensuring consistent heat and a safe environment
pro tip | rock collection
a wise sauna stove manufacturer once gave me the following advice for collecting your own rocks:
two, overflowing five gallon buckets hold about one hundred and fifty pounds of rocks. a five gallon bucket full of rocks, however, is too heavy to carry. take four buckets and fill each of them a little more than half way full.
her stoves [ ilo sauna stoves ] carry approximately one hundred and fifty pounds of rocks
when rock collecting, respect public lands
more detail on rock collecting [ here ]