Brush rust particles from the wrought iron banister with a broom. Use a smaller whisk broom to reach into tight areas or inside grooved indentations.
Fill a bucket with 2 cups of white vinegar. Dip a cloth into the vinegar and wipe it over the remaining rust on the banister. Allow the vinegar to remain on the rust for 10 minutes.
Buff the rust from the wrought iron with an 80-grit sandpaper. Use slight pressure, rubbing the sandpaper back and forth over the rust stains until removed.
Rinse the banister with a garden hose or a bucket of water and a sponge. Dry the wrought iron with old towels.
Apply a liquid car wax to the wrought iron to prevent rust from forming on the banister. Wipe the wax over the banister with the supplied applicator or a micro-fiber cloth.
Remove the wax after it turns cloudy by buffing it off with old towels.