People, especially turners, are often surprised to hear that a bowl can be dry and ready for finish carving in as little as a couple weeks after carving it from green wood. I don’t know much about turning, but from what I read and hear, those turners that begin with green wood on an electric lathe typically take the bowl down to about 75%, leaving a significant amount of extra wood, then dry it very slowly in chips or whatever for several months or even over a year before returning it (a particularly appropriate term in this case) to/on the lathe for the final stage. Of course, some turners will turn green wood with no intention or possibility of putting it back on the lathe after drying. In such cases, the piece is taken right down to final size while green. But that’s another story.
For two-stage carving and turning, the difference in the amount of wood removed and drying time comes down to the fact that a (standard) lathe makes things round. The bowl, carved or turned, will move and change shape as it dries. Round bowls will dry to an oval (unless you carved it oval to begin with). In the case of turning, the concentric nature of the lathe means that it will not recognize and go along with the movement that has occurred during drying, therefore, more material needs to be left at the green stage so that, as the bowl is returned to truly-round on the lathe, there is enough extra material where needed.
Meanwhile, I typically remove just about all of the wood during the green carving stage, call it 95%. Like the bowls in the photo above, the final form is clearly established. The bowl will move and distort pretty predictably as it dries, and carving allows the freedom to go along with those changes. Additionally, the fact that most of the designs I carve are not round, but oblong, means the movement usually occurs symmetrically on either side of the longitudinal axis, so there are few aesthetic issues with the movement.
Removing so much green wood allows moisture to escape more easily and evenly during the drying process, making faster crack-free drying more possible than if only 75% of the wood had been removed. Of course, there are factors applying to individual situations with various pieces of wood and designs. I’ve got a general post about drying here.
There is still plenty, usually most, of the work to be done after drying, which is one of the reasons many carvers have lots of unfinished bowls lying around their shops. I’m going to be working my way through this stash. Meanwhile, I just finished a bowl by starting with a dry (9 years dry) block of walnut; that story coming up soon in my next post.