4.1 This test method is designed to measure the vertical distance between any two levels on the face of the flooring, that is, between any two flat areas, between a flat area and any part of a textured area, or between two textured areas. This vertical distance may be of interest in itself or it may be applied to the questions of: (1) how much of the thickness of the flooring is available before the pattern is destroyed; or (2) how deep the depressed areas must be before valley printing ink is not walked on in normal traffic.
1.1 Two important characteristics involved in the manufacture of resilient flooring relate to the smoothness of the wear surface and the hardness of the layers under the wear surface. The surfaces may vary from completely textured areas to portions that are flat but separated by textured areas. This test method covers flooring with these interrupted wear surfaces which are not supported by soft, cushioned layers.