How is Powder Coating Applied

The application of powder is very simple. Filtered, compressed air, usually at 20 - 30 psi pushes the powder out of the gun past the electrode which gives the powder a positive charge. The part being coated is grounded so the positive powder particles are attracted to it. The object is then heated, and the powder melts into a uniform film, and then is cooled to form a hard coating. It is also common to heat the metal first and spray the powder onto the hot substrate. Preheating can help to achieve a more uniform finish but can also create other problems, such as runs caused by excess powder.
Before the powder is sent to the gun it is fluidised to separate the individual grains of powder and so improve the electrostatic charge that can be applied to the powder and so that the powder flows more easily to the gun.

Because the powder particles are electrostatically charged, the powder wraps around to the back of the part. The powder will remain attached to the part as long as some of the electrostatic charge remains on the powder. To obtain the final solid, tough, abrasion resistant coating the powder coated items are placed in an oven and heated to temperatures that range from 320 to 410 degrees F depending on the powder.

Under the influence of heat a thermosetting powder goes through 4 stages to full cure.

MELT, FLOW, GEL, CURE

The final coating is continuous and will vary from high gloss to flat matt depending on the design of the powder by the supplier.