What kills rust before painting?

What kills rust before painting includes chemical rust converters, rust removers, and mechanical methods that stop corrosion and prepare surface for paint adhesion. Rust is iron oxide that continues to spread if not killed or removed. Chemical rust converters contain tannic acid or phosphoric acid that react with rust to convert iron oxide into stable black iron tannate or iron phosphate that can be painted over, stopping further rust. Popular converters include Rust-Oleum Rust Reformer, Corroseal, and POR-15 Rust Converter. Rust removers like naval jelly, which contains phosphoric acid, dissolve rust completely, leaving bare metal, and include products like Loctite Naval Jelly, Evapo-Rust, and WD-40 Specialist Rust Remover Soak. Mechanical methods that kill rust include wire brushing with stiff wire wheel on drill, sanding with 80 to 120 grit sandpaper to remove loose rust, grinding with flap disc, and sandblasting for heavy rust. After removal, apply rust-inhibitive primer such as Rust-Oleum Rusty Metal Primer or KILZ Original to seal. For light surface rust, vinegar soak or baking soda paste can remove. For best results, remove loose rust mechanically, then apply chemical converter, then prime with rust-inhibitive primer, then topcoat. Ensure surface dry and keep gutters clean to prevent water causing future rust.