Sterling grade carbon blacks are classified as semi-reinforcing with the exception of Sterling C which is a conductive black. During careful manufacturing techniques, the impurities of the standard grade blacks are reduced. Impurities like hard particle carbon grit, metallic rust, stainless steel, aluminum salts, sulfur, etc. do affect physical and surface properties of elastomeric vulcanizates. Compounders have seen physical improvements especially in dynamic properties (flex fatigue), ECD (electrochemical degradation), tensile strength, elongation, tan delta, surface appearance, hot tear resistance, etc. utilizing these carbon blacks. Also, due to their cleaner nature, these blacks have contributed to smoother injection, extruded and compression molded stocks, lower scrap rates, improved dispersion, fewer screen changes and less wear on production equipment.