I've turned 2 NE walnut bowls one at ¼" and one a little less. I turned both with continuous curves no straight walls and they are 15 inches on the long side. I'm in N GA and the weather is cool and humid. I left one bowl out on a shelf and bagged the second. Both bowls cracked after a couple of days. I know you have to pay your dues while learning the process but I sure need some advice on this problem. You all know the quote " to continue to do the same thing and expect different results is insanity" or something close to that. I tried some Danish oil on a smaller bowl to try to stop the cracking and after a few days I tried to sand but it just gummed the sandpaper. I've prepared 3 more blanks and have them in plastic bags until I get each one turned. I'm open to and appreciate any suggestions.