08/17/2026
Canadian sauna builder Mark Lacroix’s finish of choice? Osmo UV-Protection Oil 410 Clear. Copperwood Sauna Co. in Spruce Grove, Alberta, finishes every sauna build with it, citing how easy it is to work with in the shop and the long-lasting result it gives clients.
Osmo UV-Protection Oil 410 is built specifically for exterior wood, which makes it a natural fit for outdoor sauna exteriors, changing rooms, and cedar cladding. It's a satin, natural oil-based finish that penetrates cedar rather than forming a surface film, so it won't crack, peel, blister, or flake the way many film-forming coatings eventually do. The microporous finish lets the wood breathe while still repelling water and reducing swelling and shrinkage, which is perfect for the extreme high and low temperatures saunas endure.
Maintenance is straightforward too: when it's time to refresh the finish, it's a clean-and-recoat process rather than a full strip-and-sand. For sauna owners, that means less time maintaining the structure and more time using it.
Whether it's a barrel sauna by the lake or a cabin-style sauna tucked into a backyard retreat, an outdoor sauna faces year-round exposure. Without protection, cedar exteriors weather to grey, and Western Red Cedar, Eastern White Cedar, and other softwoods commonly used for sauna builds can start to crack, cup, or absorb moisture unevenly. That's where sauna wood protection comes in, not to change the character of the wood, but to help it hold its natural colour and structure for years.
We recently caught up with Mark Lacroix from Copperwood Sauna / Forest Trek Woodworking, read the full Question & Answer on the Osmo Blog.
