No matter what you plan to paint, preparation is essential to success. Different surfaces require different painting methods and materials for a good outcome. Understanding why it’s important to prepare metal parts before painting will help you remember and complete the necessary steps.
Preparation Makes Metal Surfaces More Durable
Metal roofs, gutters, downspouts, and railings will last longer and endure weather better if they are painted. But if you paint without proper preparation, you could end up with peeling, flaking paint. Water and winter de-icing salts will get under the paint, causing corrosion and rust.
Some types of professional preparation that are done in metal shops or manufacturing facilities, such as shot blasting or shot peening, strengthen metal, helping it resist cracks and corrosion. In these methods, the surface is blasted with steel shot to dislodge dirt, rust, and old paint. On a smaller scale, jewelers use a process called “work hardening” to ensure jewelry that’s made of softer metals stiffens and holds its shape. It’s important not to overdo it because, as the metal gets harder, it also gets more brittle. Overworking the metal can cause it to break.
Preparation Makes Paint Stick
Paint and other coatings adhere better to smooth, clean surfaces. That’s why it’s so important to remove rust, dirt, old paint, and any grease or oil from the metal surfaces you intend to paint. A smooth metal surface that’s free from imperfections will allow coatings and paints to adhere evenly across the surface of the part, so you can avoid missing any spots.
Used parts may be especially in need of extra processing to prepare them for paint. Many metal shops that work on parts for automobiles and machinery use vibratory finishing or rotary tumbling equipment to file off “burrs” or little imperfections in metal that has been cut, bored, stamped, or heated. These processes also smooth and polish the surfaces of metal parts, preparing them for protective coatings or paint.
Proper Preparation Improves Appearance
In addition to cleaning, part of the preparation process for metal surfaces involves repair. Fixing dents and holes will result in a smoother and more pleasing appearance when you’re finished. Brushing and sanding to remove rust and using the correct primer—usually, a rust inhibitor that’s rated appropriate for the type of metal you’re painting—will result in a smooth paint application that simply looks better.
If you intend to paint a metal surface or metal parts for auto repair or embellishment, it’s worth the extra time to prepare the metal surfaces for painting first. Your paintwork and the metal under it will last longer and look better as a result.