In 1974, Chem-Pruf founder William V. Pitt designed, engineered and built the first successful industrial fiberglass door that would not bow, rack or warp. This remarkable door was made possible by a unique, now patented, one-piece fiberglass stile and rail system. Tough, corrosion-resistant fiberglass door plates which form the faces of the door were permanently bonded to the stile and rail to create the finished corrosion resistant door. With an idea, a feat of engineering and a wealth of manufacturing know-how, Bill Pitt founded not only Chem-Pruf Door Company but an entire industry. Chem-Pruf continues to set the standards with industry firsts": First patent ever issued by the U.S. Patent Office for an atmospheric-resistant door. First to mold a solid, all-fiberglass door frame. First to tailor resin chemistry to match the exact conditions where the products will be installed. First to introduce a unitized fiberglass door system with the door pre-hung in a color-matching fiberglass door frame and all hardware installed at the factory prior to crating. First to offer a 25-year warranty against failure due to corrosion. First to manufacture a complete fire-rated fiberglass door and door frame system certified and labeled by Warnock- Hersey.