Powder Coating Pretreatment Process

Manufacturers across a wide array of industries are turning to powder coating as their preferred method to protect their equipment. That’s because the process ensures better adhesion and coverage compared to traditional wet paint applications. With industrial powder coating, the completed piece has a highly durable finish that can resist numerous environmental and chemical hazards. It’s no wonder, then, that the procedure has become standard for agriculture, defense and automotive sectors.

However, the enhanced durability of these finishes would not be possible without a robust powder coating pretreatment process. This differs from the typical paint pretreatment, but ultimately leads to a stronger bond between the substrates and coatings. What follows is a brief overview of how coating pretreatment works and why it is necessary to achieve the best overall results.

What is Powder Coating?

Before learning about the powder coating pretreatment system, it is important to understand what powder coating is and how it is applied. Unlike standard paints, this coating is a dry powder consisting of polymer resins, pigments, curatives and other added ingredients. It resembles baking flour in many ways, especially with its uniform consistency and fine particles.

To cover a piece of equipment, the mixture is forced through a spray gun that applies an electrostatic charge to each particle. To help attract the powder to its surface, the unit is usually grounded. After the entire surface is covered, the part is placed in a curing oven. There, the intense heat causes a reaction that permanently bonds the powder and creates a seal. Once completed, the finished components are ready for assembly or sale.

How Pretreatment Works and Why It Matters

Just as you would sand or use a primer before applying liquid paints, pretreating surfaces is crucial to ensure that the powder coating sticks. Without this critical step, impurities on the substrate may interfere with the integrity of the finish, which could lead to bubbling, flaking or corrosion. Professionals understand the importance of creating the cleanest possible exterior before attempting to coat it.

In cases where a fresh coat is being applied to an existing component, the first step should be to remove any existing finishes and/or rust. In an industrial environment, this typically is accomplished through sandblasting. For newly manufactured products, sandblasting is unnecessary, so these units move to the next step: chemical cleaning. Most powder coating pretreatment chemicals are alkaline based in order to remove any oils, dirt or other contaminants.

Once the chemical cleaning is finished, the next step is to etch the surfaces and apply a conversion coating, such as iron or zinc phosphate. This is to provide a layer to which the powder can adhere with greater success. A final rinse in water treated with an acidic solution completes the pretreatment process. The item is now ready to be coated.

Choose Rhinehart Finishing

As part of our comprehensive powder coating capabilities, Rhinehart Finishing follows an extensive pretreatment protocol that goes above and beyond the industry standard. In fact, we use a zinc phosphate cleaning system that is certified by the Department of Defense and approved for military applications. This level of protection can potentially extend the life of your equipment and enable it to withstand the wear and tear of repeated operation.

The professionals at Rhinehart Finishing have considerable experience with the common types of coatings, including epoxy, polyurethane and hybrids. Plus, our state-of-the-art production facility includes one of the most advanced coating booths in the industry. We also offer one of the largest product window sizes in the Midwest, capable of handling items up to 12’ x 3’ x 6’. Simply put, trust Rhinehart Finishing for superior, expert pretreatment service.