Polyethylene Coating: The top layer is a waterproof plastic film that gives the tape its characteristic sheen and, most often, a silver or black color. This layer provides resistance to moisture and abrasion.
Fabric Mesh Backing: The middle layer, known as the scrim, is a woven fabric mesh, typically made of cotton or polyester. This reinforcement is the source of the tape's durability and strength. It allows the tape to be torn by hand along a straight line, as the fabric threads provide a guide for a clean rip, while also preventing it from tearing easily in other directions.