Animal Fibers
. All animal fibers are complex proteins . They are resistant to most organic acids (see Acids and Bases ) and to certain powerful mineral acids such as sulfuric acid. However, protein fibers are damaged by mild alkalies (basic substances) and may be dissolved by strong alkalies such as sodium hydroxide. They can also be damaged by chlorine-based bleaches, and undiluted liquid hypochloride bleach will dissolve wool or silk. The principal component of silk is the protein fibroin. Silk is exuded in continuous filaments from the abdomens of various insects and spiders. It is the only natural filament that commonly reaches a length of more than 1000 m (more than 3300 ft). The only silk used in commercial textiles is produced from the cocoons of the silkworm . Several silk filaments can be gathered to produce textile yarn. However, silk is often produced and used in staple form to manufacture spun yarns. The principal component of hair, wool, and fur is the protein keratin. Individual hair