Randy, I spent TWO DAYS years ago trying to resolve this exact problem with Hydromist White and came up with the conclusion that it was the paint. No matter what I did I'd get cracking hours later. White is the only Hydromist paint I've ever had issues with. I use Polytranspar Super Hide White now and have had zero issues with it. I get better coverage out of it vs. the Hydromist White. I dumped nearly a full quart of Hydromist White into the trash - it's JUNK!!!!
X-2 on the Super Hide White. Might give Paul's a try though just to compare......