SAUNA Made in Finland

by Matti Karjanoja

Finland has an interrupted sauna tradition going back a couple of thousand years or perhaps even more, and the sauna has in principle remained almost unchanged throughout that time. It can really be regarded as a national custom, as 90% of Finns still go to sauna once a week. It has been calculated that there are 1.7 million saunas in Finland, i.e. approximately one for every three inhabitants. The sauna is part of life for people of all ages, both as means of washing and as a ritual, so that a Sunday or holy day is still preceded by sauna the evening before. Indeed, sauna itself is regarded almost as a sacred event, so that it is improper to quarrel or swear in sauna. It is still customary to offer visitors to one's summer cottage a sauna bath, and sauna is automatically included in summer excursions, meetings and visits, to such an extent that some people who are not devotees are heard to speak of 'sauna terrorism'.

Although the technique of bathing by throwing water onto heated stones was not invented by the Finns, it is an institution that they have maintained and developed, and they have become masters of the art in its modern form. The sauna can in fact be regarded as the joint heritage of the Finnic peoples of the Baltic region, as shown by the existence of the word sauna in all their languages. The practice is also known throughout the Baltic States and Northern Russia. The difference between the sauna and the bathing practices pursued in other countries lies in the fact that the humidity of the air in the hot, dry sauna is altered periodically by throwing water onto the hot stones. The sauna was the first building to be erected by settlers at a new site, and it was often located beside a lake or river, which would have been the primary transport routes at that time. The oldest type of sauna, like the oldest type of dwelling, was merely a hole in the ground, and this remained common for a long time in treeless areas. With the development of interleaving joints, a type of building was introduced which had a chimneyless stove. The room filled with smoke, which was cleared through small ventilation holes after heating. This chimneyless one-room hut was originally used for a variety of purposes, and people may even have bathed in it, but later the sauna gained a building of its own, although this may still have been used for threshing as well, and perhaps temporarily for living in.

The western and eastern parts of Finland differ in many aspects of their folk culture, and the sauna is no exception. Thus people in Western Finland usually go to sauna once a week and used to use the sauna building for household purposes in the meantime, to dry plant fibres for spinning, to cure meat, to malt and dry grain and to wash clothes, whereas in Eastern Finland the sauna was only used for bathing and could be heated more frequently, perhaps as often as ten times a week, particularly when clearing land for slash-and-burn cultivation.

It was traditionally the custom for the entire family to go to sauna together, as the fire had to be put out before people could enter and the sauna held its heat only for a certain length of time in the early evening. This included all generations and the hired workers as well, and led in turn to the habit of everybody being in sauna together regardless of sex in the early industrial communities, even in the case of strangers. This persisted in the public saunas as urbanization proceeded, and continued to be a natural state of affairs in Finland up to the early years of the 20th century. Later it became normal for men and women to go to sauna at different times or use separate saunas.

The sauna building

The construction of the sauna has in principle remained unchanged for centuries. It consists of a panelled room in a separate building or part of a building which is heated to a high temperature by means of a stove covered with stones. Its special character lies in the quality of the hot, dry air, which alters in humidity as water is cast on the heated stones. It is important to create the correct balance between heat, humidity and ventilation, and it is this that places certain technical requirements on the construction of the building.

The basic type of Finnish sauna, irrespective of size, is a rectangular building of interleaved timbers rising up directly from the ground, with a door in the centre of the wall at one end. At one time some saunas used to be partly sunk into the ground, as this made them less expensive to build. The sauna formed one of the buildings lining the enclosed farmyard in Western Finland, but in the east it was placed outside the yard on account of the danger of fire, often beside a suitable well or spring. This meant, of course, that it had to have some kind of shelter in front of the door in which the people could undress, and this was sometimes achieved by driving stakes into the ground, which could be hung with spruce branches in the winter. The most common way was to build a gable over the door and construct board walls beneath it. The shelter could also be made of logs or stones.

The building of saunas has developed along with other construction techniques. Once hewing became more common, the round logs used at first gave way to straight, carved logs. The oldest buildings had plume joints at the corners, and this was followed by straight corners, while ornamental clasp or dovetail corners were fashionable in the 1920's and 1930's. Eventually the interleaving log construction of the walls gave way to vertical boards in urban sauna buildings.

The first saunas stood on bare ground, but it was later common to cover the floor with stone labs, loose boards or poles, and eventually floorboards and concrete floors were introduced as building techniques advanced.

The roof was traditionally made of birch-bark, straw, peat, boards or beams. Shingled roofs became more common in the 19th century. Initially the ceiling and outer roof were connected, so that the form of the ceiling was dependent on the design and shape of the roof, but later the ceiling came to form a completely separate element.

There are many details characteristic of sauna architecture, such as the style of the doors, hinges and handles, and the overall simplicity of construction.

Hot water was not used in the sauna at all in former times, so that one only poured cold water over oneself or went out to roll in the snow.

From clay stoves to electric sauna

The hot air in the sauna is generated by means of a stove covered with stones that are heated to a temperature of 300 - 800 degrees. The quality of the sauna mainly depends on the type of stove. The oldest type is a vaulted heap of natural stones of different sizes, with the smallest ones on the top. Later it became customary to build a permanent structure of stones or bricks to form the body of the stove. The smoke came out into the room from an opening in the stove and from between the stones and was removed via a small smoke vent. The simplest saunas had a bench against the far wall, but the usual pattern was to have a raised structure of seats, typically held up by pillars or logs in the eastern part of the country and by beams in the west.

Stoves began to develop early in the 20th century, when they came to be manufactured with a sheet metal casing and fittings for a chimney. This led in turn to the continuously burning stove, in which the fire grate was encased in metal and the stones were heaped on the solid top of this, so that they were not in direct contact with the fire or smoke. This is the same principle on which modern electric sauna stoves operate. With time the metal casing has changed shape, from a tall, round barrel to a low, rectangular structure, including modern models in which the stones have been replaced with a flat surface. The most recent patent to be issued is for a triangular stove that can be heated by either wood or electricity and has a soapstone slab on its front surface, against which the water is thrown.

Stoves are constantly being improved, but the literally hundreds of models in use today all fall into one of six categories: smoke stoves, single-fired wood-burning stoves that are extinguished before bathing, continuously fired wood-burning stoves, ordinary electric stoves, electric storage stoves, and special gas or oil-fired stoves etc.

The sauna should ideally be heated using dry wood. Split birch logs release the most heat relative to their weight, whereas aspen is the poorest of the Finnish woods from this point of view. Coniferous wood tends to leave soot and tar in the chimney and produce a crackling noise, but alder is ideal for heating a smoke sauna, as its embers burn away quickest of all and leave no smoky tang behind. If the stove has to be extinguished before bathing, some water should be thrown onto the stones while the damper is still open, to remove any smoke and eliminate all possibility of carbon monoxide fumes. Then close the damper and let the temperature in the sauna even out.

Hard, dark-coloured igneous rocks are best for use on sauna stoves, preferably ones containing olivine, pyroxenes and iron and chromium oxides, as they will not crack easily nor release any unpleasant substances. They should have a large surface area, so that they will not cool down too quickly. An electric stove made of metal should in particular have plenty of stones on it, to prevent the water from falling onto the heating elements, which will generate a large number of detrimental positively-charged ions.

The ideal temperature for a sauna is 80 - 100 °C measured at the height of the bather's head, with a maximum range of 75 - 105 °C, while the temperature at floor level should remain at 30 °C. The humidity of the air should ideally be 50 - 60 g of steam per kg of dry air. This will mean a relative humidity of 10 - 40 % at a temperature of 80 - 90 °C.

Apart from ensuring that there is enough room for all the people to sit comfortably, the size of the sauna is important from the point of view of heat distribution, ventilation and the size of stove needed. The aim in terms of ventilation is to remove excessive water vapour and allow a change of air in the sauna. The Finnish sauna typiccally involves fluctuations between dry and humid heat, and its wooden walls also store heat to some extent, radiating it back at the bathers from all sides. If the heat came only from the stove it would have an unpleasant toasting effect.

The interior of the sauna should be entirely of wood, ideally old, seasoned logs darkened by time. The benches are usually made of aspen, which stores heat without its surfaces becoming excessively hot. Various forms of panelling have been developed for saunas that form one room in a house, but the same traditional, straightforward designs are still preferred for the furniture and fittings.

The sauna should have dim lighting, as this has a relaxing, calming effect. New means of creating the right atmosphere are currently being explored, including the use of optical fibres.

© Matti Karjanoja. All views expressed in this article are those of the author and do not necessarily represent the views of, and should not be attributed to the European Commission.