Duct tape is made of three separate layers, polyethylene, a cloth mesh and a rubber-based adhesive. While both synthetic and natural rubbers can be used to make the glue, natural rubber adhesive lasts longer than synthetic rubber adhesive.
The polyethylene, the same plastic used in grocery bags, is waterproof and the tape gets its gray color from a powdered aluminum, which is added to the polyethylene when it is produced. The cloth mesh can be made from cotton, polyester, nylon, rayon or fiberglass and makes the tape a stronger material. While other adhesive tapes have been used before, duct tape was developed for military use during World War II.