A manufactured fiber composed of regenerated cellulose in which substituents have replaced no more than 15% of the hydrogens of the hydroxyl groups (Federal Trade Commission definition). Rayon was the first major commercial synthetic fiber. There are three primary fiber production methods for rayon. The first, developed in 1890, was the cuprammonium process (see cupro fiber). The second, and the most widely used process, called viscose, was developed in 1892. Viscose rayon can be further processed to form high tenacity and high wet modulus rayons (see modal and polynosic fibers). The third method for making rayon fibers is to saponify cellulose acetate fibers (see acetate rayon). Rayons are used for woven and nonwoven fabrics, rubbers, felts, tire cords and cellophane.