One thing I forgot to mention in my previous post. I saw a video on utube that showed a production bowl shop in Michigan (I think)and they steamed their bowls after coring. I don't have a steamer, but I do have a canning pot on the stove that will boil water (during the winter).
I had made a set of bowls out of a beautiful birch burl from and for a good neighbor and the second largest bowl developed a 1/4 inch wide crack from near the rim all the way to the bottom. I was upset and thew it into the canning pot and left it there for a day. I pulled it out and the crack had sealed shut! I CA'd the crack and bagged it and set it on the floor to dry. Hopefully it will stay shut.
I have seen other videos that promoted boiling as a drying method. They used a turkey fryer and a 55 gallon drum. The claim is that it speeds up drying and equalizes internal stresses to eliminate cracks.
Good luck
Tom