It’s a lot like painting, with half the mess! Powder Coating has a few very distinct advantages over conventional paint aside from it’s toughness and durability factors.
The powder particles are a dry, almost dust like consistency compared to the liquid based paints which have pigments suspended in a solution that has to dry out. In a clean setup using only one color, powder coating over spray can actually be recycled and used again and again until 100% of the powder is used up. In contrast, once paint is sprayed, it’s pretty much there for good, and there’s no looking back.
Powder Coating also supplies the piece with a far thicker coating then conventional paint, which is a key to it’s durability. In fact, powder coating a piece compared to painting it will result in it’s finish being approximately 10x thicker, and with it’s baking process, or flow out as some call it, it comes out smooth as glass with absolutely no orange-peel.
A powder coating gun has a polarized rod running through the center of it, which basically charges the powder particles running past it. The steel will have a ground strap running of it, to basically complete this ‘static charge’ type situation it’s looking for. Since the powder is now positively charged from the gun, and the piece is holding a slight negative charge from the unit, the powder actually clings to the piece you’re working on. At low air pressures, you can actually see the powder make turns in mid air to find the path of least resistance to the ground (i.e. the parts of the piece you’re making with the lightest coating). This significantly reduces the amount of powder over spray by utilizing up to 95% of the powder exiting the gun on some systems and settings.
The act of curing the powder is done by raising the temperature of the powder coated piece past the flow out temperate of the powder you’re using. This will vary depending on the different types of powder available, but basically what it boils down to, is melting that dry powder that is clinging to the part. As the temperature comes up, the powder melts, and some powders actually re-align their chemical makeup to add further strength properties to it. After the part has been heated up for the powder to flow out, it is removed from it’s heat source (often an oven, but can also be heat lamps) and cooled to room temperature slowly so that the powder and the piece come down to room temp at the same time.