Other Powder Application Systems

In addition to spray application with electrostatic guns, powder coating materials can be applied by a dip method called fluidized bed. Fluidized bed powder coating was developed by Edwin Gemmer for application of thermoplastic resins and patented in 1953.

In fluidized bed coating, parts are pre-heated to 450–500º F and then dipped into a tank filled with powder material that has been “fluidized” by addition of compressed air through a porous membrane located at the bottom of the tank. In some cases the powder is electrostatically charged.

Another option is flame-spray application. In flame-spray, which is used to apply thermoplastic powder materials, powder is propelled through the flame in a heat gun using compressed air. The heat of the flame melts the powder, eliminating the need for ovens.

Yet another method of application is called hot flocking. In this process, the part to be coated is preheated so that the sprayed powder will gel when it comes in contact with the hot part surface. Hot flocking is often used for functional epoxy application because it builds a thick film that will provide exceptional performance. These fusion-bond epoxy (FBE) products are often used to coat valves and pipe used in extreme conditions such as oilfield or offshore applications.