Duct tape consists of three components: A polyethylene surface, a cloth grid, and adhesive (more on the adhesive in a bit). The polyethylene serves as a bonding surface for the other two components and provides a waterproof backing. The cloth grid, or scrim, ultimately influences the tape's strength, flexibility, and tearability. The threads that run the length of the tape determine its material strength, or how much weight it can hold before breaking. The closer the threads that run across the tape are spaced, the cleaner the tear.