I am planning to use Tung Oil on the walnut-bodied bass I am currently building. However, from reading the various posts in this forum, it has become unclear to me whether I should be using pure tung oil alone or further coating with something else like shellac, varnish or a light coat of urethane. Or are there pre-mixed tung oil/varnish products I should be using (kind of like Ken Smith's "Secret Sauce" which I guess is not for sale). Can any of you help clarify my Tung Oil options? Thanks.