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Sealing a Sauna

Interior Sauna Sealer

Should a sealant be applied to a sauna? This is a very popular question! The environment inside a sauna is harsh, it can be 200 F inside with burst of humidity as well as salty human perspiration can quickly damage or stain the wood. As with all wood, if left untreated it will certainly age quicker. We recommend sealing the inside of a sauna especially the wooden benches with a special waterproof sauna sealant.

This water-based sealant has no off gas even in high heat and will not discolor the inside of the sauna wood like other stains. It goes on like water quickly being absorbed into the wood. Once dry the sauna sealant will repel water and perspiration leaving the wood looking new.

Wood without a sealant will tend to stain the wood. When water penetrates the wood, it dissolves the pigments of the natural tannins in the wood. As the water dries and evaporates, it brings with it the pigments to the surface forming a water ring that is a permanent stain with no way of being removed other than a hard sanding of the wood.

Water stains on un-sealed sauna wood

Besides the seats, the ceiling and corners of a sauna room are also susceptible to water stains especially in a wet sauna (adding water to the rocks). The steam tends to condense on the corners of a sauna room and can ruin the appearance of the beautiful wood.

Prevents Mildew-Besides stopping water stains, a properly sealed sauna will also help prevent mildew that can be caused by the water and high humidity level. Mildew can quickly spread and cause a mold smell to a sauna room if left untreated.  Cleaning the sauna room periodically with a special sauna cleaner, will also help to prevent mold and odors from forming. Another practice is to leave the sauna “on for 15 minutes after being used to dry it out should there be lots of moisture.

The outside of a sauna room may also be stained depending on the type of wood used. In this case the sealant is completely different the sealant used inside a sauna. An exterior sealer will have lots of UV protection in it to prevent sun damage from discoloring the wood. Harsh rain and snow can also quickly break down wood fibers causing premature aging of the wood. If it is an interior sauna room inside a house the outside of the sauna may be left untreated provided it is not in direct sunlight.

How to apply-Apply the sauna sealant using a 2”-3” fine hair paint brush. Do not use a coarse staining brush for the inside as they tend to lose hairs and leave brush strokes. When staining always brush with the grain of the wood. Have a rag handy to wipe off any drips that may occur in areas such as the seats. Once sealed, follow the manufactures instructions for drying times before using the sauna.

Applying a light coat of sauna sealant to the entire inside of the sauna room every couple of years will ensure your cedar sauna looks new and protect your investment.


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