30″ x 60″ fiber reactive shark menace beach towel picturing a single large mako shark, with its mouth open, swimming toward the surface of ocean. Fiber reactive dyes form permanent covalent bonds with the cellulose fiber in cotton. This enables the towels to stay bright for years. Fiber reactive dyes are permanent dyes. Unlike inks, they do not rest on the fabric or coat the fabric; they chemically unite with the molecules that make up the fabric. They become part of the fabric. .