SW Kem Aqua is my go to finish and I always add GF extender to it. I spray 3 mil with it and measure with a wet mil gauge. Recoat in 30 minutes. I've read it takes about a month to fully cure but I've never checked. I just spray, let dry for a day after final coat and install. The Kem Aqua surfacer (primer) can be sanded to a powder within half an hour as well if sprayed at 3 mil.