After the roughed bowls were dry (no longer loosing weight) I finished turning a couple and finished them with the usual shellac/wax finish (Crystal Coat). In two days they were sticky.
I wiped them down with acetone and sanded down to the bare wood. Applied two coats of polymerized tung oil (Lee Valley). They looked good for nearly a week then the sap mixed with the tung oil and made a wrinkled soft mess over the heartwood.
Scraped and sanded to the bare wood, applied two coats of Bull's eye shellac, using 0000 steel wool after each coat was dry. Again used the polymerized tung oil. Same result only it took longer to wrinkle up.
Scraped, sanded, acetone then 4 coats of shellac until a slightly glossy finish, then two coats of tung oil. So far this has stayed hard and the grain shows well. The only problem is getting a level coating each time, requiring steel wool to even it up.
I would have never fooled with the stuff if it hadn't been for the sentimental value of the tree and folks wanting bowls from it.