How do you clean mildew on wrought iron stair rails?

To clean mildew from wrought iron stair rails, start by mixing equal parts water and white vinegar or using a mild detergent solution. Apply the mixture with a soft brush or cloth, scrubbing gently to avoid damaging the finish. Rinse thoroughly with water and dry the rails to prevent rusting. For stubborn mildew, a commercial mildew remover specifically designed for metal surfaces may be used, following the manufacturer's instructions.