This would have been my second bowl.

[Kenneth Whiting 79]

I put this maple blank on the lathe and got started on it. I walked away for a couple hours and saw these cracks when I got back. Mounted on the lathe in the pictures is a piece of cherry that started splitting while I was turning it.
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[George Morris]

Ken I could not open your picture. In my limited experience I will not leave a bowl I start. I go from start to rough or finish. If you have to leave it I would wrap it in a plastic bag to keep moisture in. It will warp very quickly if it dries on lathe. Good luck and keep at it ! G

[Doug Herzberg]

+1. Saran wrap and grocery bags help a lot.

[Kenneth Whiting 79]

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This is what was supposed to be up there.

[John Thorson]

If rough turning with green wood I agree that you need to stick with it until done and then seal, bag or do whatever you are going to do to slow the drying. If turning green (high moisture) wood to a finished piece all in one go the suggestion of wrapping with plastic helps. If this was a final turning of dry wood I believe these cracks were probably in the wood before you started and 'opened up' more as the piece dried even further on the lathe.

[Chip Sutherland]

I duplicate the comments on Saran wrap and grocery bags. When I have had to leave the piece on the lathe overnight, I have also tossed in some of the chips from the piece into the bag or into the bowl if hollowed out some. I will even dampen a paper towel and toss it in. It is not common for me to start a piece and leave it without going to a rough state at least. It is only a few minutes more for me to dismount the piece and toss into my DNA box. I only learned what to do by making the mistake and then finding out how to address it from forums like this one.

[Kenneth Whiting 79]

This was a blank that was already "dry". I'm thinking the cracks were already there.