What is Powder Coating?

Powder coating is a method used to apply a protective and decorative coating to products such as white goods, aluminum extrusions, and automobile and motorcycle parts. Newer technologies have allowed other materials, such as medium-density fiberboard (MDF), to be powder coated using different methods. First used in Australia in 1967, powder coating has become one of the most popular surface finishing techniques in use today.

Powder coating uses a very fine dry powdery-resin that contains a color pigment. The resin is charged by electrostatic methods and then using a spry gun is applied to the metal surface. Because the powder is charged it will adhere itself to the surface of the metal. The metal is then placed inside an industrial oven and baked at approximately 400 degrees or more, which will cause the powder to allow it to flow and form a skin that is more uniform and durable finish, which is resistant to chemicals, wear and tear, and chipping.

Powder coating has a far better impact resistance, flexibility and corrosion resistance than that of liquid paints. Powder coating is a very cost saving and effective alternative to liquid paints. In addition, in compared to liquid paints, powder coatings are environmentally friendly, because they are regulated and free from pollutants.

Powder coatings are most commonly applied by spraying the powder on, using an electrostatic gun, or Corona gun. The gun conveys a negative electric charge onto the powder, which is sprayed on the object that is grounded. Once the object is coated, it is then heated, melting the powder causing it to form a hard coating. Some powder coating company?s use a technique in which they heat the metal prior to spraying the powder so that the powder goes onto a hot surface, however this can lead to problems such as runs caused by excess powder. Another process uses a different type of spray gun called a Tribo gun. The Tribo gun charges the powder by friction, in much the same way you create static electricity by walking across the carpet. The powder becomes positively charge from being rubbing along the sides of a Teflon tube located inside the barrel of the gun. Once charged, the powder particles then adhere to the grounded substrate. However, when using a Tribo gun, it requires a different formulation of powder than that used more commonly in the Corona or electrostatic guns.

The Fluidised Bed method is another method of applying powder coating. With this method, the substrate is heated and then dipped into an aerated, powder-filled bed. The powder adheres and melts to the hot object, and then further heating is required to finish curing the coating. The Fluidised Bed method is most often used when there is a need for the thickness of the coating to exceed 300 micrometers.