New Bar’s Leaks Carbon Fiber Block Seal Head Gasket & Cooling Sealant (p/n HG1) is an antifreeze-compatible cooling system repair that fixes cooling system leaks, including blown head gaskets, its maker said. The product permanently seals any coolant leaks in plastic, cast iron, copper and aluminum radiators, heater cores, freeze plugs, gaskets and intake manifolds. Its formula combines liquid glass (sodium silicate) with aramid and refractory fibers the same materials used in bulletproof vests and fireproof clothing. The formula is further reinforced with carbon fiber to bridge larger leaks. It also features a proprietary wetting agent to improve heat transfer and reduce coolant temperature to help prevent overheating and future leaks.