I'm finally getting around to transforming a large chunk of cedar that's been sitting in my basement into a mantel for our stone fireplace. I need to stain it and put a protective finish on it but am worried about the effects of the heat coming up from the wood stove beneath it. I typically use water-based stain and poly on wood projects but I'm not sure that's the way to go with the mantel. Since poly is basically a plastic(?) I'm thinking that the elevated temps above the stove may soften or degrade it. Anyone have an experience/thoughts on this.