Anyone have experience with earthen plaster inside saunas?

I'm looking at putting together a wood fired hot tub and setting the stove inside the small structure the tub will be against thus turning said structure into a suana. This way, I could sit in the sauna while my tub water is heating. My concern is what all the steam will do to the clay paint covering my earthen plastered walls. One wall is earthbag and the other three chip slip. All share the same plaster and clay paint.

Common sense tells me the paint will turn to mush. One thought was to wax all the walls to prevent damage. But then, the heat might cause the wax to come off. Another thought was to use olive soap as is done on Tadelakt. I have no experience with this though....and don't know how the soap would look on the paint or if it would withstand the heat.

I could apply a lime plaster but these walls have many sculptural elements which are pigmented and polished with a thick coat of wax. I could remove the wax, cover everything in lime and re-color the sculptural elements in the process. That would be more work than I have time/ambition for though.

Anyone have experience in this realm?

Hey Rusty, I thought you had left us for good. Glad you're back.

I wonder if a lime plaster would work ? They run water pretty well and the hot moist environment may hasten the hardening process.

I will eventually create a spa with plate glass sheets set into the cob. With silicone caulking on all joints, I'll have an earthen look with the ease of cleaning that glass affords. Plate glass is often free when scrounged from commercial projects where the store fronts are upgraded.

Hey Dale! Thanks for the kind words. Bouncing from project to project and from interest to interest, I haven't had the time to spend here that I would like. It's good to still see you around here. It's a great community.

Any way, yes...I think lime would be a good choice...but, in my case, it would, as I mentioned, be more work than I had time and ambition for. I keep thinking about the bees wax idea. The sculptural elements are already waxed.

Attached are a few pics of the inside.