POR15 is a high-tech, high performance rust-preventive paint like coating, designed for application directly on rusted or seasoned metal surfaces. It dries to an incredible rock-hard, non-porous finish that won't chip, crack, or peel, and it prevents rust from recurring by protecting metal from further exposure to moisture. Most common use it to coat rusty frames, floor pans, farm equipment, marine equipment, or even a heavily corroded battery trays.