Hollow alumino-silicate microspheres, 300 micron top size - a genuine lightweight filler for polymers, cement and drilling fluids.
Cenospheres are the hollow spheres that float off fly ash. They are inert, rigid, thermally insulating and float on water, which makes them a filler that takes weight out rather than adding it. Used in syntactic foams, lightweight cement, refractory linings, oilfield fluids and automotive composites.