Full definition
A single-component liquid adhesive that cures (polymerizes) when confined between close-fitting metal surfaces in the absence of air (oxygen). The metal ions (particularly iron, copper, and their alloys) catalyze the acrylic-based cure reaction. Three major application categories: (1) Threadlocking — prevents vibration loosening of bolts and screws; grades: low (purple, hand-removable), medium (blue, wrench-removable), and high (red, requires heat for disassembly). (2) Flange sealing — replaces cut gaskets on machined metal flanges; fills gaps up to 0.25 mm; resists oil, coolant, and gas. (3) Retaining compound — secures bearings, bushings, and cylindrical assemblies in housings; fills gaps up to 0.15 mm; cures to structural adhesive strength. Typical shear strength: 15-35 MPa on steel. Temperature range: -55 to +150°C (standard), +230°C (high-temperature grades). Cure speed: fixture in 5-30 min, full cure 24h at room temperature; accelerators available for inactive surfaces (stainless, zinc, aluminum). Per MIL-S-46163. Brands: Loctite (Henkel — market originator and leader), Permatex, 3M, and Hernon.