If I turn green wood to finished size what should I seal it with on the inside and outside? I plan to turn some and let them dry slow but I will also turn some "ART" as daveo is fond of saying.
When I turn green to finished I use the same finish that I use on most of my turnings...BLO and paste wax, sometimes rattle can shellac or lacquer.
No finish is going to seal the piece from the movement of moisture, so just let it happen. As long as you turn to an even thickness throughout and watch out for sanding heat the piece might warp but it won't crack (unless it has some internal flaws/stressors, and there is nothing that you can do to prevent that).