Although versions of the powder coating process were being experimented with prior to 1950, fluidized bed powder coating did not gain much traction until the 1960s. The popularity of spraying the powder coating with a gun that electrically charged the powder coating particles become popular in the 1960s and 1970s as well. Both methods are still in use and provide some excellent advantages over other coating processes for suitable applications. (Related reading: Coatings Advances: Nanoparticle Technology and Cold Sprays.)
How Powder Coatings are Applied
One of the most popular methods used to apply powder coatings is electrostatic gun spraying. During this process, the spray gun not only propels the electrostatic paint, but gives them a positive electrical charge as well. The base material is charged negatively, thus creating an attraction between it and the negatively charged powder coating particles. Once the attraction between the two is established, both are heated until the powder coating particles melt and adhere to the base material. The base material is then allowed to cool and a durable powder coating is created.
Another common method to apply a powder coating is the fluidized bed method. To perform a fluidized bed operation, a base material is heated. Once the base material reaches a specified temperature, it is immersed in or fed through an aerated bath or bed of powder coating particles. The heat from the base material causes the powder coating particles to melt and adhere to its surface. The base material is then allowed to cool and the coating solidifies.
Safety Advantages of Powder Coatings
One of the most important advantages of powder coating materials over liquid coating materials is that they can be much safer for the operator. Applying a powder coating typically requires an operator to wear a dust mask and safety goggles. However, many powder particle types do not emit any fumes. This means that as long as they are not being accelerated, they are relatively harmless if they are not inhaled or ingested. This is very different from paints that have volatile organic compounds (VOCs) or other solvents in them, because these chemicals can cause serious respiratory and neurological damage if inhaled excessively.