Powder coating is a finishing process in which a coating is applied electrostatically to a surface as a free-floating, dry powder before heat is used to finalize the coating. The powder can be made of any number of products: polyester, polyurethane, polyester-epoxy, straight epoxy, and acrylics. Powder coating is a finishing process that yields a thick, hard finish that is tougher than conventional paints. Powder coating can be found on a range of products, from household appliances to automobile parts.
Powder coating can be accomplished through one of two processes: thermosets and thermoplastics. Thermosetting involves additional chemicals which react to the powder during heating. Thermoplastics have no additional chemicals and instead just melt and flow into the final coating. Both processes of powder coating look quite similar except for this distinguishing feature. The thermoset or thermoplastic powder is created by taking the powder input and binding the items together, heating the mixture, rolling out the product, and then breaking the polymer product into chips which can be ground into a fine powder.
Each of the processes of powder coating typically after the powder is created by preparing the metal to be powder coated. The object is cleaned with a particular attention to the removal of any debris and oil which can inhibit the attachment of the dry powder. Next, the dry powder is applied electrostatically—a process by which the particles of the powder and the object are charged through a high voltage electrostatic surge. This electrostatic stage of powder coating greatly increases the efficiency and productivity of the coating process by nearly 95%. Less paint is wasted and the metal object is fully coated.
The sprayed powder coating is then cured at temperatures as high as 400 degrees for ten minutes so that the finish can set onto the object. While setting, the powder melts and flows around the object. The heat not only melts the powder but binds the polymer into a heavier polymer that bonds in a tight network-like finish. The curing not only coats the sheet metal product, but it also binds the polymer into a tighter, heavier finish.
The benefits of the process of powder coating are numerous. First, powder coating results in a thick, dense finish on metal products which can be more durable and longer lasting than conventional painting. Second, powder coating is typically a one coat finish so the process can be quite quick and easy. Third, powder coating can include multiple custom finishing colors and textures as the powders which are sprayed onto the item can be expertly manipulated. Fourth, powder coating is an environmentally safe finishing process because it produces few volatile organic compounds. Finally, powder coating creates the most even finished surfaces (horizontal and vertical surfaces) because the powder is sprayed and heated across without drips or application traces.