Wax/asphalt-based underbody mastic bonds to metal. repels moisture. salt spray. corrosion and abrasive wear under the cars bottom. Forms a strong barricade against rust and corrosion. When dried, it leaves a relatively hard, black protective layer. which does not smear or melt. Very good sound insulator. reduces noise reaching the cabin. Also suitable for processing tanks. gas pipes. brake cables. hydraulic pipes. agricultural machinery and metal structures.