Powder Coating has been around for about 50 years.  It was developed when they found a formulation for a finely ground "plastic" powder.  That was the beginning of the powder coating industry. 

The process of powder coating is done by first cleaning the part to a dry, bare metal surface, a special electrostatic spray gun with 30,000 to 90,000 volts, is used to apply a thin layer of "plastic" powder onto the surface of the part to be coated.  The powder is held onto the part by static electricity.  Kind of like dust on a TV.  Once coated, the part is oven baked at approximately 400 degrees Fahrenheit.  The curing oven melts the dry powder to a "gel state" and then further curing causes this gel to harden into a very tough "plastic" coating.  This flowing and fusing of the coating in the final curing oven creates a continuous coating which is very hard and has no porosity.

Now for the WHY?  Powder Coating does not use solvents, there are no toxic chemicals released into the air, thus EPA regulation do not add expense to this process.  Also, for about the same cost as professionally applied paint, powder coating offers a superior finish combined with an excellent durability that will extend the life of the part.  It is particularly beneficial for parts exposed to harsher conditions such as moisture and chemicals.  Powder coating does not fade and is very chip and crack resistant, flexible, and can be applied to all metals.

The unique characteristics of powder coatings provide superior consistency and uniformity of finish without sags, drips, runs, or bubbles. They provide extremely tough, durable films, enhancing the high quality, value-added image of consumer products. In general, the performance properties, such as impact resistance, flexibility, and corrosion resistance, of powder coatings are better than with liquid paints. Powder coated parts resist cracking, peeling, and marring during handling and normal service use. In many cases, merchandise is specifically being advertised as "POWDER COATED" because of the quality image it projects.