Dinitrol Converust RC900 forms an impenetrable barrier to oxygen & moisture. Ideal for cavities, panels & under-body work. Loose & flaking material should be removed but it is not necessary to clean down to bare metal. This Aerosol version of Dinitrol Converust RC800 converts rust to a stable organic iron compound. Dries to a hard black film ready for fillers or topcoats. 400ml aerosol.