For EPDM roofs, apply a “flash coat” (a very light coat) approx. 200 sq. ft 1.5 gallon resulting in 6-8 Mil. Then, let the flash coat dry for at least 24 hours. Cooler temps or high Humidity may retard cure times. Then apply the main coat at 40 sq. ft per gallon, resulting in 20 mil thickness.
If Flash coat is not completely dry solvents are still gassing off and will cause wrinkling if main coat is put down before flash is dry. This will extent time needed to flatten out and dry.