Septone Rust Prime is a water based chemical that converts rust to an inert black compound and simultaneously primes and seals the metal surface so that it is ready for subsequent priming and top coating. Rust Prime will provide temporary protection against rust, but should not be considered as a corrosion resistant coating. Primer coats and top coats should be applied as soon as possible after the surface has been treated with Rust Prime (and within 4 weeks) .