I have turned four vase/hollow forms and two of them have had a problem where the rims would crack severely during turning before closing after they sat around and were done for some time. It has happened with Willow and Yellow cedar, one wet and the other dry respectively. Why would they do this and how do I stop it or avoid it? The wood is not dripping wet, or hot. Is there something about the thin rim at high speeds causing cracking? If so, why did the other two vases out of cottonwood not crack? It is quite upsetting, especially when the rest of the piece is not cracked and suddenly 6-8 cracks are spreading and growing so quickly you can hear it. Maybe the vibrations? On a slightly different topic, I have had a couple of pieces of almost dry wood crack immediately upon a finish/glue being applied, has anyone else had this happen or know a way to avoid it?