The dry film thickness (DFT) of coatings on concrete can be accurately determined using a paint inspection gauge, which is specifically designed for measuring the thickness of dry coatings. This method provides a direct measurement and ensures compliance with the specified DFT required for the coating system. Paint inspection gauges, such as magnetic or ultrasonic types, allow for reliable readings that reflect the actual thickness of the applied coating after it has dried.
Using other methods, such as a wet film gauge, would not provide an accurate DFT measurement. A wet film gauge measures the thickness of the coating while it is still wet, which cannot translate directly to the dry thickness after curing. Similarly, estimating DFT based on the quantity of coating used is inherently unreliable because it fails to account for factors such as application technique, substrate absorption, or coating characteristics, all of which play a significant role in the actual thickness achieved once the coating has dried.
Therefore, the use of a paint inspection gauge is the preferred and correct method for verifying DFT on concrete.