I took a section of black walnut branch log, about 12" diameter, very green, and turned the outside of it for a hollow-form vase. Here's a picture, after roughing out the outside. The pith is perpendicular to the lathe spindle, through the center of the log. All of the bark and most of the sap wood has been turned away; it is mostly heart wood now.

I also drilled a hollowing pilot hole, about 1" diameter, 6" deep, using a forstner bit mounted in the tailstock. The vessel is mounted on a face plate.

IMG_20220105_195216524.jpg

I'm thinking about how to deal with the drying process. With something like this, I'm not sure the "rough to thick walls, dry, then re-turn to thin walls" approach would work. I think the distortion and cracking would make it difficult to re-turn it after it dries.

I'm thinking about a different approach. This approach would be intended to make it dry from inside the hollow form, not from the outside. I hope that this would make the outside of the vessel more resistant to cracking.

To do this, I'm considering applying a multi-coat (2-3) clear epoxy finish to the outside of the vessel, BEFORE hollowing out the inside. Once the inside is hollowed to the desired thickness (say, 1/4"), it would be able to dry, though somewhat slowly since there's not a lot of air circulation through the small opening used for the hollowing. The wood on the outside would not be able to "breathe" because it would be coated with epoxy, which is waterproof and impermeable, so I think the shrinkage and stress on that surface would be less. Surface cracking due to drying of the inside surface wouldn't be a problem to me, unless the cracking extended through the wood to the outside surface. And the epoxy should offer at least SOME resistance to that cracking, acting as a nearly spherical semi-rigid constraint on the outside of the vessel.

Any thoughts?