How to Paint Metal: Instructions & Types of Paint
Using spray paint or a standard paintbrush, it's easy to refresh metal at home
Painting metal is different than painting other surfaces, and the material is challenging to work with. Paint doesn’t stick as well to a metal surface as it does to wood or plaster. Also, metal is prone to oxidation and rust. When painting on metal, it’s essential to use a paint formulated for metal, especially if you want to control rust and weathering.
Types of Metal Paint
Metal paints come in oil-based and water-based brush-on or spray-can versions. Oil-based paint is trickier to work with, but the results are longer lasting. Water-based acrylic paints can be overall more forgiving but may be difficult to find in spray form for exterior use. Learn more about choosing paint types and several steps needed to prepare the metal for painting.
- Spray-can paint offers the easiest way to paint metal. It is especially useful for pieces that have many contours, such as patio furniture or wrought-iron fences or railings. But the finish is usually not as smooth and uniform as with brush-on paint, and it may take several coats to achieve the desired finish. Good ventilation and a respirator are essential when spraying paint. You may have trouble finding water-based spray-can paints.
- Brush-on paint takes considerably longer to apply, but the finish will be smooth and durable. Both water-based and oil-based versions are widely available.
Primer is a must for painting metal. If the metal surface has been painted before, you'll need to remove old paint, rust, debris, grease, and dirt using sandpaper, a scuffing pad, or wire-brush tool. If the metal is smooth and has nothing on it, you'll still need to scuff up the surface of the metal by sanding so the primer can stick to the surface. The scuffing pads or sandpaper will also help smooth away some metal imperfections.
Anytime you're working with metal, make sure to protect yourself. Use a dust mask or respirator, protective goggles, and gloves. Also, work in a well-ventilated area. When grinding away rust with a wire rotary tool, use earplugs for ear protection.
What You'll Need
Equipment / Tools
- Shop rags
- Scuffing pads
- Dust mask or respirator
- Wire brush or wire brush drill attachment
- Natural bristle paintbrush (optional)
- Water-based acrylic paint or oil-based paint for metal
- Rust remover (optional)
- Mineral spirits (optional)
Identify the Metal
Different metals require different primers, so begin by identifying the type of metal you'll be painting. The basic distinction is between ferrous (iron-based) and non-ferrous metals. Ferrous metals include steel, cast iron, and wrought iron. These metals will be susceptible to rust—which likely will already be evident in areas where the previous paint job has chipped or worn through.
Non-ferrous metals include aluminum, copper, stainless steel, and zinc. These metals will require a different type of primer than that used for ferrous metals. Some ferrous metals are galvanized with a thin outer layer of zinc to prevent rust; these can be treated as non-ferrous metals when it comes time to prime them.
Remove Old Paint and Rust
Use a wire brush to remove any loose or flaking paint and as much surface rust as possible. If a handheld wire brush is ineffective, consider using a wire brush attachment for your drill for highly degraded surfaces. If the rust has penetrated deep into the surface, soak the object in an appropriate rust remover and follow all steps as specified by the manufacturer. Wipe the surface with a damp cloth to clean any dust, debris, or rust that’s left over. Remove the remaining grease by wiping the metal with a shop rag dipped in acetone. Allow the acetone to dry.
Scuff Up the Metal
If the metal doesn't have paint on it or it's smooth, take a scuffing pad and rub it along the metal. These pads will lightly etch the surface of the metal, which will allow the primer to stick more effectively.
Full sanding is usually not necessary unless the metal is badly corroded. With galvanized metal, sanding can potentially abrade away the zinc layer and make the metal more likely to rust in the future.
Prime the Metal
Priming metal before painting is almost always recommended, as it will prevent rust from bleeding through the new paint. Primer also helps paint stick to metal.
If you couldn't get rid of all the rust in the previous step, coat the metal with a zinc chromate primer that's formulated for coating rust.
After you have coated the area with this special primer, apply a coat of self-etching primer. This primer should be specifically designated for either ferrous or non-ferrous metal and should incorporate a self-etching component. Read the label to verify that metals are an intended surface. The last consideration for primer is to be sure the primer is compatible with the paint you want to use since a primer can be either oil-based or water-based.
Closely follow the instructions on the primer label since they have different drying and cure times. If the metal is going outdoors, consider adding a second layer of primer to help delay metal oxidation.
If you're debating whether to use spray paint or a paintbrush, the easiest way to paint metal is to use a can of spray paint. It is faster, but it does not create as hard of a finish.
Here's how to use spray paint:
- Shake the can several times to mix the paint.
- Hold the can 6 to 12 inches away from the metal, which will prevent the paint from pooling. Spray the object using long, sweeping motions (don't hold it in one spot). If you notice excessive dripping, wipe clean, back up, and start the process again.
- For best results, apply up to three thin coats of spray paint and allow the paint to dry before applying an additional layer.
If you want a longer-lasting finish, brush on the paint using oil-based paint. By painting the metal object with a brush, you can create a thick surface that will be more durable.
Painting metal using a paintbrush:
- Mix the paint according to the manufacturer's specifications. If the paint feels too thick, it might need to be cut with some mineral spirits.
- Once the paint is a desirable consistency, use a high-quality natural bristle brush to paint on a thin layer.
Allow the Paint to Cure
The metal needs to cure for 36 to 48 hours before moving it. Ensure the object is in an area that won’t be affected by extreme temperatures or direct sunlight when drying.
When to Call a Professional
Items that have significant rust may need the help of a professional painting contractor to see if the metal is salvageable or can be restored. You can even take appliances like washing machines and clothes dryers to an auto body shop and have them do the work. You'll get a hard, professional finish, but it can be a bit expensive.