There's tung oil and there's tung oil.
Real tung oil takes months to cure and was used by the Chinese for centuries to waterproof their boats (junks).
Then there is 'tung oil finish' that is commonly seen on the shelf of many big box hardware stores. Sadly this stuff usually contains less than 5% tung oil. It looks pretty, dries fast but it is not a durable finish. Save your money.
There is an outstanding product that I've been using for close to 2 decades that will seal and waterproof any wood and is extremely durable. Its called Waterlox Finish and Sealer (red can). Downside is if you don't know how to store it properly it will gel in a few days once you open the can (let me know if you want to learn how to store it).
In your case I would suggest you purchase a good spar vanish (the better ones cost a bit more). This type of finish is commonly used for outdoor furniture and boats (Marine Spar Varnish). Its easy to apply and won't gel for a good while if the lid is properly closed. You could even squirt some inert gas into the can before closing the lid and the finish may last a couple of years. Spar varnish should hold up to the abrasive qualities of clay.
IMO bees wax and mineral oil is the worst possible finish to use (I'm biting my tongue before I say more)