With a paint gauge? I guess it works on clear coat also
Paint Meter, Paint Gauge, Paint Gage - HighLineMeter.com
Thickness- this can be checked with a paint thickness gauge. Bear in mind that a clear coat has a thickness of 1.5 – 2.0 Mils, removing more that 0.3 – 0.5 Milsof clear coat may cause premature paint film failure. As a point of reference a sheet of Saran wrap measures 0.95 Mils. Most car manufacturers now specify that the paint thickness be measured in 0.1mil, or 1/1000th of an inch before and after any wet sanding or buffing. If only 0.4 mils of clear coat have been removed the integrity of the clear coat may have been compromised. The following are the maximum allowable clear coat reductions the major USA car manufacturers will allow: Chrysler – 0.5 mils; Ford – 0.3 mils; GM – 0.5 mils.
Paint thickness gauge - PosiTest DFT Combo; Measures paint on any metal; including steel and aluminium, a popular choice given many cars have both steel and aluminium. It automatically recognizes the material and takes a measurement-http://www.autopaintgage.com/