Thermally sprayed coatings are applied to various substrates for the purpose of providing a wear-resistant, corrosion-resistant, or heat barrier surface. The materials used to coat a substrate will vary in hardness with respect to each other and with respect to the substrate. Denser coatings produce more reliable hardness data than less dense coatings due to the absence of pores and other inconsistencies in the coating. Variations in coatings will cause preparation problems such as pullout, edge rounding, or coating-to-substrate relief which effects the reliability of hardness determinations. The repeatability of hardness data is directly related to the density of the coating. This paper deals with the effect of coating characteristics (density) on the reliability of manual and automated hardness measurements.