I have built a 42 inch by 7 feet 1 inch thick black walnut table for my daughter and son in law's new house. I am in a friz of how to finish it. They want tung oil from seeing my other projects. I don't think tung oil is durable and needs to be repeated on occasion. If I did tung oil can I seal it with polyurethane? Give me any details about it you can.