Inherent versus Treated Flame Resistant FabricsWhat are the differences between “inherent” and “treated” flame resistant fabrics?Inherently flame resistant fibers are materials that have flame resistance built into their chemical structures. Aramid fibers from companies like DuPont create inherently flame resistant fibers, with brands such as DuPont™ Kevlar® and DuPont™ Nomex®. The actual structure of the fiber itself is not flammable. For inherently flame resistant fibers, the protection is built into the fiber itself and can never be worn away or washed out. In the case of Nomex®, when exposed to flame, the aramid fiber swells and becomes thicker, forming a protective barrier between the heat source and the skin. This protective barrier stays supple until it cools, giving the wearer vital extra seconds of protection to escape.