Gary Davis also mentions on the DVD that he Liberally coats his staves with Varnish,
or Clear Polly or what ever he is currently using Before steaming to help cut down on negative effects of the steam on the wood.
On a side note he also mentioned in passing, on the video, that Tung Oil Might work, but only if enough coats were applied to build up a thick finish,
10 to 20 coats or maybe more... not his first choice.
I have used Tung Oil for steaming staves, Osage and Dogwood.
Seems to work okay, but the prep time to get the needed thickness of finish is too long for my taste.
Think I'll be using Varnish or Clear Poly in the future.
-gus