These are used by industrial coatings laboratories, principally those involved with the automotive industry, to measure the hiding power of spraying enamels. The chart is attached to a steel panel and the test coating sprayed to produce a "wedge" varying from thin at one end to thick at the other.

After drying, a location on the chart of adequate visual hiding or 0.98 contrast ratio is determined, and the film thickness measured electronically on the steel panel adjacent to that location. Conversely, a location of specified thickness is determined on the steel panel and the contrast ratio measured adjacent to that location.

Available in Black/ White, Grey/ White and, for the S71, Red/Grey