Arc-resistant molding materials and finishes

A means has been found to increase the arc resistance of certain organic materials which otherwise are inferior in this property. By incorporating any of a number of inorganic submicron refractory fillers, the American Society for Testing Materials (ASTM) arc resistance of phenolic and substituted phenolic molding compounds and a number of non-arc-resistant finishes can be greatly increased. Both the percentage and the particle size of the filler added are important factors. Data are presented describing the effect on arc resistance of these variables. A proposed mechanism presenting a possible explanation for the effects described in this paper is presented.