3M™ fiberglass matting adhesive is a low viscosity two-part urethane used to saturate fiberglass cloth or mat when preparing backup patches. Our adhesive may also be used for filling cracks, channels and areas restricting the application of an adhesive bead. Due to its excellent absorption into fiberglass mat or cloth, 3M™ fiberglass matting adhesive is used to saturate fiberglass cloth and/or mat when creating backup patches for Sheet Molded Compound (SMC) and Fiber Reinforced Polyester (FRP). Examples of FRP include fiberglass and Metton® panels. If bonding reinforcement patches to flexible plastics or Metton® use 3M™ polyolefin adhesion promoter, part number 05907 before applying the patch.