Thickness gages are used to make precise dimensional cross section measurements on a wide variety of coatings and materials including steel, plastic, glass, rubber, ceramics, paint, electroplated layers, enamels, pavement, multi-layer deposits, etc.  There are many mechanical gaging, nondestructive and destructive techniques available to accomplish this task: IR or nuclear gauges, eddy current, magnetic particle, laser, ultrasonic, coulometric, and X-ray, are only a few of the many techniques.