Powder coating as a finish has a lot of benefits and drawbacks which you can learn more about here. It is often chosen for its durable finish, its environmental friendliness, and lower variable cost in comparison to liquid coating. Despite its greater durability, even powder coating is susceptible to experiencing abrasions and damage over time. When scratches or abrasions occur the underlying material can be at increased risk for oxidation. Whether to prevent oxidation of a substrate or to restore cosmetic appearance of your product both are good reasons to apply liquid paint over a powder coated surface. The short answer to if you can paint over powder coating is yes you can however you have to do so while paying attention to a few considerations. In this article will cover what you need to consider when applying liquid paint over powder coating.
Challenges to Applying liquid paint over Powder Coating
- Adhesion – Adhesion refers to the ability of a coating to bind to a particular surface. The challenge with adhesion when painting over powder coating is that powder coating can often create a very flat, smooth surface. This can create challenges when trying to have a liquid coating properly bind to the underlying substrate.
- Matching Coating Performance – Powder coating is highly resistant to scratching, wear, and weather. When trying to paint over an existing powder coating you often want to have a liquid coating that will have similar performance characteristics of the powder coating though you will usually not be able to achieve the exact performance of the original powder coat.
How to overcome The Challenges of Applying Liquid Paint over Powder Coating
- Prepare the surface appropriately to overcome adhesion challenges – Since Powder coating usually forms a smooth surface after applied, you have to roughen the surface to create a surface profile so that your coating can create a bond. You can create a bond by sanding the bare area as well as the edges of the bare area where there is still powder coating in place. Typically, you should use a fairly light grade sandpaper. After properly sanding the area to be painted you will want to wipe the area with an appropriate solvent cleaner. If there is a larger area that you will repaint like a construction vehicle you may want to sandblast the damaged area as it will be a faster process.
- Choose a Correct Coating or coating system – To maximize the life of your repair work you will want to select a coating system that will provide performance characteristics that will be similar to the performance of the original powder coating. The ideal coating system will depend on the environment your product will function in and the primary concerns of your product whether it be appearance or performance. Ultimately you will want to consult with a coatings representative to ensure the coating will endure like your original powder coating.
- Apply the coating – There are a variety of methods to apply a coating and the right one for your product will depend on the amount of painting you will need to perform as well as the finish you want to achieve. To get a good overview of different ways of applying coatings you can read about different application methods here or give us a call and will help determine what might be right for you.
Important considerations of painting over an existing powder coating
- The degree to which the powder coating is intact – If the underlying powder coating is missing in multiple locations and significantly more is missing than is in place you will typically be better off removing all the coating on the product and starting new this will most often require sandblasting to remove the existing coating.
- The degree of substrate oxidation – If the substrate has significant rust you will most likely want to sandblast the surface rather than sand it as you will need to remove a significant amount of the surface to provide a rust free substrate for application of the new liquid coating. Failure to adequately prep the surface can result in poor coating performance or even failure of the new coating.
Painting over an existing powder coating is possible and can be helpful when you need to repair a powder coated surface. It is important to consider the extent of damage to the underlying powder coating, the right paint to use to paint over the powder coating, and properly preparing the surface for the liquid coating. By considering all these variables, you can ensure that you will be able to repair your powder coated product with a liquid coating that will be able to perform well.