Pure tung oil. I've also had nice results with 1/3 tung oil 1/3 polyurethane, and 1/3 mineral spirits. Makes a nice wipe on finish that's forgiving. Pure tung oil is by far my favorite, in good part because ot can be touched up in one spot, or recoated with no evidence of repair or need for stripping. Great protection, and it brings out a depth of the natural beauty ofnthe grain thays just unmatched by any other finish.