As a simple test, I took a 3/4" x 5" x 9" sheet of walnut, did a quick sanding, and then coated each of the two surface faces with a different brand of Tung Oil. Two nights ago, we took a 2 qt pot of boiling soup right off the gas burner and put it on the block. Last night, a ceramic pan came right out of a 400 F oven onto the other side of the trivet. In neither case was any degradation or discoloration of the finish seen. FWIW, each side received 4 coats of its Tung Oil a day apart and the whole thing was set aside unused for over a week. From this I'd conclude that at least for "fully cured" oil, the finish would stand up to trivet use with no problems. Norm