Wet Film Thickness Test
Wet film thickness gages are used to monitor the thickness of the applied wet coating to achieve a specified dry film thickness. They measure all types of wet organic coatings, such as paint, varnish, and lacquer on flat or curved, smooth surfaces. The units of measure for these gages is typically micrometers (microns) or mils. Wet film thickness is measured according to ASTM D4414, Standard Practice for Measurement of Wet Film Thickness by Notch Gages. Pictures are gages commonly used to measure WFT.
Measuring the WFT of a coating enables the applicator to adjust the spray gun speed, number of spray passes and to make spray gun adjustments (when possible) or select other spray tips to apply the correct amount of coating to achieve the specified dry film thickness.