Loctite instant universal low viscosity toughened gel amp flexible adhesives loctite 4850 loctite 4850 is designed for the assembly of difficult to bond materials and is specifically formulated to provide flexible bond lines it provides rapid bonding of a wide range of materials including metals plastics and elastomers when used to bond rubbers for example loctite 4850 maintains the full compressibility of the joint it is particularly suited for bonding porous or absorbent material