It was raining hard, but I had just finished a new version of my 180' coastal tanker, so I couldn't wait to spray it with Krylon flat black. On a covered porch, I placed the hull on a small turntable, gave the can 300 shakes (about two minutes) and sprayed away. Went back in about half an hour. The flat bacl was more like dark gray, with some areas only light gray.
Like Krylon clear spray, flat black frosts under severe humidity. It was absolutely perfect for a weathered black hull. I might have spent an hour trying for the effect with an airbrush.