A method for measuring the spark-shower radiance of metals when abraded on an abrasive grinding wheel was developed for evaluating their sparking tendency. One hundred metals were tested and rated relative to commercially pure iron. The radiance was measured in units of energy per solid angle per area of the detector. The metals tested included elemental metals, iron binary and ternary alloys, iron-carbon ternary alloys, commercial steels, nonferrous alloys, and a few hard-metal compounds. Some alloys were synthesized, others were obtained commercially. Alloys which possessed good strength properties were emphasized for selection. The results indicate that the spark-shower radiance of plain carbon steels and carbon alloy steels was greater than for pure iron. Certain elements, particularly vanadium and chromium, reduced the sparking tendency of iron. Stainless steels and particularly nickel alloys displayed low spark-shower radiance. Some metallic elements had much lower radiance than iron, others much greater. Plain-carbon steels, heat treated to a variety of hardnesses, gave radiance values which gen erally increased with increasing carbon content and hardness, but showed a decreasing radiance trend at high levels of carbon and hardness.