Gauges using magnetic principles offer a simple and effective method to measure coating thickness on a magnetic subtrate. Electronic coating thickness instruments can be supplied to measure:  

Non-ferromagnetic materials on a ferrous sustrate. Any nonconductive material on a conductive substrate.
Destructive methods for both ferrous and non-ferrous materials on non-conductive surfaces such as wood, concrete, plastic or glass using a test employing a precision cutter and optical measurement.