When painting a baseboard heater, apply two coats of either a water-based paint or rust-inhibiting paint designed for metal surfaces. Applying two coats of primer prior to painting is recommended to help adhere the paint to the metal surface.
For best results, prepare the surface of the baseboard heater before painting by removing any rust and loose or chipped paint with a scraper, wire brush and sandpaper. Sand the entire surface with a fine grade sandpaper, then thoroughly clean all dirt and dust from the baseboard heater using a clean cloth. Allow the surface to dry completely before applying primer.