Things You'll Need
Auto body filler (Bondo)
Metal doors are often used in place of traditional wooden doors in homes and commercial buildings. They are made from steel for added strength and durability, and will last for years with fairly little maintenance. These doors are typically painted to match the surrounding decor, and can be repainted to cover scratches and other signs of damage that occur over time. To get the best possible results, it is important for installers to clean and prepare these doors before painting to remove dirt, rust and grease.
Remove the door from the opening. You can use a hammer to drive out the hinge pins, or simply unscrew the hinges from the door. Set the door on a pair of sawhorses so you can easily access the entire unit. Remove any remaining hardware, then cover windows or louvers with painter's tape so they are protected during the painting process.
Scrape away rust spots by rubbing them with a piece of steel wool. Work carefully to avoid damaging the surrounding surface, and make sure all rust is removed before proceeding.
Peel or scrape away loose paint. Use a paint scraper to chip away flaking paint sections, as well as any areas of paint that seem to be sitting loosely on the door's surface. Test other areas to see if they can be easily scraped away. Paint that is in good condition and is not chipping can be left on the door and painted over.
Fill holes or dents with auto body filler. This product is often referred to as "Bondo," after a popular brand name. Mix the filler according to the manufacturer's instructions, then fill holes with a putty knife. This will minimize the risk of rust at these dented spots in the future, and will create a smooth, even surface for painting.
Apply a small amount of mineral spirits or acetone to a damp rag and use it to clean the door. Work carefully to avoid spills, and make sure the room is well-ventilated when using these products. Clean all door surfaces, including the edges, as well as the trim or molding around windows or raised panels. Once all dirt and grease are removed, wipe away remaining cleaning products with a clean, dry cloth.
Choose your paint carefully. Even after your door has been cleaned, it is still critical that you choose the right type of paint to cover any existing paint on the door. If you have existing latex paint on the door, you can apply only latex paints and primers. If your existing paint is oil-based, it's safe to use either latex or oil paints. Avoid applying oil paint over latex, as this creates a cracked, flaky finish that will need refinishing fairly quickly.