For me, VHT was easier to use than Krylon when I painted my hemi valve covers. For the VHT paint it didn't really make a difference if it was 60 degrees or 90 degrees outside. It was easier to paint when it was cold because the layers dried slower. Also the wrinkle was coarser when it was cold. When you spraying the paint you want the layers to be as thick as possible without it running. Apply the next coat when you start to see wrinkles starting to form. 3-4 thick coats of paint works well. You can do it with more thin layers of paint, but the idea is to get it thick before it dries. Another tip is shake the can a couple of minutes before each coat.