Old cast iron radiators can add to the charm of an older house; however, they also are prone to rust and peeling paint the older they are. This detracts from their aesthetic charm and can be a health hazard, particularly if the rusted area are sharp or if the paint is lead-based. You can prevent further rust and correct the rust and peeling problems already present by cleaning, sanding, priming and painting your old radiator. Using primer and paint that has a rust inhibitor will help significantly in maintaining the fresh and sharp look of the new paint job.
Sand the peeling paint and rust from your radiator with 80-grit sandpaper. Clean the area thoroughly of paint chips and rust and wipe down the surface of the radiator with a wet cloth.
Sand again with a finer sandpaper (150-grit) to smooth the area completely. Clean and wipe down again, drying thoroughly.
Apply an oil-based primer with a rust inhibitor in it to the sanded areas. Check to make sure the primer has a rust inhibitor. Use a flat, wide paint brush for the application and be sure the area is covered evenly. Paint hard to reach areas with a smaller paint brush. Allow the primer to dry.
Apply a paint that has a rust inhibitor to the entire radiator once the primer has dried thoroughly. Paint multiple layers over the areas from which you removed the rust. Allow to dry thoroughly before touching the radiator or turning on the heat.
Wear a face mask and protective eyewear while sanding and painting the radiator.