Dry Film Thickness (DFT) is the thickness of a roof coating after it is dry or fully cured. Use the solids by volume property to quickly compute application DFT using the following formula:
Measure a 10′ x 10′ (100sf) area. You may use traffic cones to mark the corners or any suitable method to mark the boundary. Spray or roll the coating while monitoring the actual consumption of product. If you run out of product before the area is fully covered, you are spraying too slowly or rolling too thick. Adjust your technique accordingly.
Dry coating thickness can be checked with a non-destructive coating thickness gauge from Elcometer and Defelsko. Accuracy of these devices can be field verified with a destructive thickness tester like the Tooke gauge.
A toothed wet film gauge is useful for verifying application thickness while the coating is still wet. Place the gauge at 90 degrees to the coated surface. Read the largest tooth that is wet.