Provided is a composition comprising fatty acid bis-amide, inorganic particulate such as pumice, cellulosic particulate, thermoplastic and maleic anhydride grafted polyolefin. The combination of an ethylene bis-amide and a minor amount of pumice produces cellulosic-thermoplastic composite that has superior extrusion properties over conventional metal stearate/ethylene bis-stearamide (EBS) compositions such as improved flex strength and resistance to water absorption.