To make a sauna infusion, mix an infusion concentrate with water and slowly pour one or two ladles of it over the hot sauna stones. The bottle tells you how much concentrate goes into one litre; for our infusions it is 10 ml. Concentrate or essential oil never goes onto the heater undiluted.
That sounds simple, and it is. Even so, many home sauna owners make the same mistakes: too much concentrate, too much water at once, or ingredients in the bucket that don't belong there. Here is how to do it properly.
What you need
- a Finnish sauna with a sauna heater and stones, heated to your usual temperature
- a sauna bucket
- a sauna ladle
- clean tap water
- an infusion product made for the sauna
An infrared cabin without a sauna heater has no stones to pour water on. A classic infusion, or löyly, is not intended there.
For the water, it is worth checking your heater's manual. Harvia, for example, states that only clean household water should go on the stones. Water with a high content of salt, lime, iron or humus can make the heater corrode prematurely, and according to the manufacturer seawater makes it rust very quickly. Normal tap water is not a problem in most regions.
The mix
With a ready-made concentrate
An infusion concentrate consists of fragrances and a solubiliser that helps the oils disperse in water. This is usually alcohol. According to a study by the German Social Accident Insurance (DGUV), the safety data sheets of commercial infusion products mostly give an alcohol content between 50 and 95 per cent.
How to mix:
- Pour one litre of water into the bucket.
- Add the concentrate as directed by the manufacturer; for ours, 10 ml per litre. A small measuring cup works well for this.
- Stir briefly so that everything is evenly distributed.
More concentrate does not make the infusion better. The scent becomes sharp rather than pleasant, and you use up the bottle faster. The DGUV also measured that infusion products release aldehydes and ketones through pyrolysis at very high temperatures. That is another reason why the stated dosage is the right guide.
A worked example: at 10 ml per litre, 333 ml of concentrate makes about 33 litres of infusion water. A ladle holds at most 0.2 litres, and people usually pour less. That gives over 200 ladles from one bottle.
With essential oils
Pure essential oil does not dissolve in water. It floats on top and, when you pour, lands on the hot stones almost undiluted. That is why ready-made infusion products contain a solubiliser.
If you want to mix your own, don't do it with oil and water alone. Germany's Federal Institute for Risk Assessment (BfR) points out that almost all essential oils should only be used in highly diluted form. And Harvia states in its heater manuals that only fragrances specifically made for sauna water may be used. The simpler and safer way is a ready-made concentrate with dosage instructions.
Which oils suit the sauna, and what to watch out for with children and allergies, is covered in the article Essential oils for the sauna.
Without oil: herbs and tea
Many recipes online use herbal brews, tea or citrus peel. That works if you keep a few things in mind:
- Strain the brew well. Plant residue chars on the hot stones.
- Don't put sugar, honey, juice or fruit pulp in the bucket. Anything that does not evaporate stays on the stones.
- Don't add salt to the infusion water. According to Harvia, salt is one of the substances that speed up corrosion of the heater.
Homemade infusions usually smell much fainter than a concentrate. If you want a strong, consistent scent, they rarely get you far.
How to make a sauna infusion step by step
- Preheat the sauna until the heater and stones are thoroughly hot. According to Harvia, no water is thrown during the very first heat-up of a new heater.
- Mix fresh infusion water and stir.
- Let everyone in the cabin know. Nobody should sit or stand right next to the heater, because the hot steam can burn the skin.
- Pour the first ladle slowly and evenly over the stones. Only pour onto the stones, not onto heating elements or steel surfaces of the heater. According to Harvia, the temperature difference can cause dents there.
- Wait a moment until the steam reaches the top of the cabin. Then decide whether a second ladle should follow.
- If you like, move the hot air around with a towel.
- After the session, pour away what is left and rinse the bucket.
Two small ladles with a pause in between are almost always more pleasant than one large one. The steam rises and needs a moment to spread.
With the Slow Steam Stone
Our hand-drilled Slow Steam Stone, made of volcanic diabase from Finland, works with the same infusion water. Instead of pouring the ladle over the stones, you use the ladle to pour the diluted infusion water from the bucket into the hole in the stone. The same rule applies here: the concentrate from the bottle never goes into the stone neat, only the finished mix of 10 ml per litre. You can read more about the stone on the Slow Steam Stone page.
Which scent for which round?
Over several sauna rounds, you can play with the scents. There is no fixed rule, but there is an order many people find pleasant: a clear, cool scent with eucalyptus or mint in the first round, something herbal and fresh later on, and a warmer scent with citrus and lavender at the end. This suits an evening on which the rounds become calmer.
If you use several scents, mix a separate bucket for each one or rinse the bucket in between. Otherwise the scent notes overlap.
How much water per infusion?
For Harvia heaters, the manual states that no more than 0.2 litres of water should go on the stones per throw, and that is exactly the maximum a ladle holds. If in doubt, the figure for your heater is in its manual.
How many infusions you do per round is a matter of taste. In small home saunas, a single ladle is often enough to make it noticeably hotter. Work your way up slowly rather than emptying the bucket the first time.
Common mistakes
Pouring concentrate neat onto the stones
Concentrates contain a lot of alcohol and essential oils, and both are flammable. None of it belongs on the heater undiluted.
Using too much
Double the amount does not mean double the enjoyment. The scent becomes sharp and overpowering.
Too much water at once
A large splash creates a harsh burst of heat. Several small ladles spread more evenly.
The wrong things in the bucket
Salt, seawater, sugar or juice damage the heater or remain on the stones.
Pouring while someone sits by the heater
The steam rises quickly and is very hot. Give a short warning and keep your distance.
If you want something to focus on during the infusion, the article Breathing in the sauna describes a simple breathing exercise for the heat.
Frequently asked questions
How do you make a sauna infusion?
Mix the infusion concentrate with water as directed by the manufacturer; for ours, 10 ml per litre. Then slowly pour one or two ladles over the hot stones, once everyone in the cabin knows and nobody is sitting right by the heater.
How much infusion goes into one litre of water?
The bottle tells you. According to a study by the DGUV, manufacturers' recommendations range from 4 to 30 ml per litre. For our infusions it is 10 ml.
Can you put essential oils directly on the sauna stones?
No. Essential oils and infusion concentrates are always diluted in the infusion water. Heater manufacturers such as Harvia only permit fragrances made for sauna water.
How many ladles do you pour per infusion?
Usually one or two. Harvia gives a maximum of 0.2 litres of water per throw for its heaters. In small home saunas, one ladle is often enough.
Can you add salt to the infusion water?
Better not. According to Harvia, salt is one of the substances that make the heater corrode prematurely.
One scent, over 200 ladles
Each bottle contains 333 ml of infusion concentrate with real essential oils. At 10 ml per litre of water, that makes about 33 litres of infusion water. Available as a set with the hand-drilled Slow Steam Stone in a wooden box for 119 €, or as a single bottle in a magnetic box for 89 €.
