Loctite 401 surface insensitive instant adhesive low/medium viscosity, clear, surface insensitive, one-part, room temperature cure, instant adhesive. Designed for OEM assembly of difficult-to-bond materials which require uniform stress distribution. Particularly suited for bonding a wide range of materials, including metals, plastics and elastomers. Ideal for close fitting applications. - Loctite 401 is designed for the assembly of difficult to-bond materials which require uniform stress distribution and strong tension and/or shear strength. The product provides rapid bonding of a wide range of materials, including metals, plastics and elastomers.