Stone used on commercial and residential floors should provide a safe walking surface in both wet and dry conditions. By measuring the coefficient of friction (COF), a quantitative number can be used to express the degree of slip resistance of a floor surface.
When the coefficient of friction is measured from a resting position, it is called the "static coefficient of friction" (SCOF). When it is measured when the surfaces are in relative motion, it is called the "dynamic coefficient of friction". Measuring the dynamic COF is difficult and requires a strict laboratory environment for accurate results. Almost all portable and laboratory meters measure only the static COF and most measuring devices (slip meters) refer to static COF. The higher the SCOF, the less slippery the surface. It is possible to have too high a SCOF; wherein the surface is actually too slip resistant and difficult to walk on.