The Power of Powder Coating
Powder Coating really is a powerful tool. And a powerful alternative to liquid paint. It’s used for appliances, automobiles, and it is the reason that rims on transport trucks look brand new. Powder coating is even key for specialized components in the aerospace industry.
Powder coat is essentially dry powder that is cured at high temperatures (+350 degrees), to provide a resilient coating on a surface. The powder can be either a thermoplastic or a thermoset polymer and are advantageous because they provide much thicker and uniform coatings than liquid paint (although it is difficult to create a consistent thin coat), produce less hazardous compounds and emissions, and tend to provide more corrosion resistance to components that are exposed to the elements.
While powder coating is a process that can be used on brand new components, it is also very valuable for restoring used products! For example, wheel rim refurbishers can transform rusted rims from transport trucks into a restored product. All through the use of particles that are on the order of the size of icing sugar particles. Who knew!
Wheel refurbishers do not deal with new materials – rather, they use abrasives to remove all rust, debris, and contaminants from the surface of a material in order to get a clean substrate. This will achieve a proper fully sealed layer of the powder. For example, on parts that will be used in extreme environments, a polyester powder will be very advantageous due to high UV resiliency and outdoor durability. Or a urethane polyester is even resistant against chemicals in addition to UV.
The powder coating process involves the following basic process:
- Prepping used parts to remove all debris
- Applying the powder
Removing all debris and abrasives can be done either chemically or mechanically, depending of the scale of damage on the component and the original material. For example, rust on steel wheel rims can be removed by blasting the material with shot at high speeds.
The powder is then applied to a material usually using a ‘gun’. The gun can be electrostatically charged, which then creates an electric charge on the powder, and is accelerated towards the grounded component via the gun nozzle to form a coating.
Lastly, the powder needs to be cured in order to transform it into a thick and resilient film. A thermoset powder melts as it cures and ‘crosslinks’ the molecules to form a polymer. This process for a thermoset powder is irreversible. Alternatively, if the powder is a thermoplastic, the process is reversible and the powder can be remoulded. The polyester powder mentioned above is an example of a thermoplastic powder.
So next time you hit the golf course, strap on your ski boots and bindings, or check out the struts on the landing gear of an airplane, it’s not just mechanics, it’s chemistry too.