How to Use a Wet Film Thickness Gauge in Paint

A wet film thickness gauge is the only reliable way to measure the thickness of a wet coat of paint or protective material. Assuring proper thickness and uniformity on a finish coat can prevent unpleasant surprises that might surface only after it's too late to correct them. If you are spraying a mold with gel-coat, this is particularly important since the first coat of material will wind up being your finished surface.

Instructions

1. • 1

     Apply an initial coat of paint.

   • 2

     Hold the gauge at a 90-degree angle to the surface and press firmly. Both corners of the gauge must touch the substrate.

   • 3

     Remove the gauge and inspect the edge. The last notch with paint on the surface reflects the thickness of the paint. The number directly above the last painted notch is the thickness reading.

   • 4

     Clean the gauge with a clean rag immediately after reading. The gauge must be free of solvents, old paint or debris to give an accurate reading.