Midwest Construction Products GFNW6 and GFNW8 is a needle-punched non-woven geotextile made of 100% polypropylene staple fibers, which are formed into a random network for dimensional stability. GeoForce Non Woven 6oz. and 8oz. resists ultraviolet deterioration, rotting, biological degradation, naturally encountered basics and acids. Polypropylene is stable within a pH range of 2 to 13.