Electrostatic spray painting
In electrostatic spray painting or powder coating, the atomized particles are made to be electrically charged, thereby repelling each other and spreading themselves evenly as they exit the spray nozzle. The object being painted is charged oppositely or grounded. The paint is then attracted to the object giving a more even coat than wet spray painting, and also increasing the percentage of paint that sticks to the object. This method also means that paint covers hard to reach areas. The whole is then baked to properly attach the paint: the powder turns into a type of plastic. Car body panels and bike frames are two examples where electrostatic spray painting is often used.
There are three main technologies for charging the fluid (liquid or powders):
• Direct charging: An electrode is immersed in the paint supply reservoir or in the paint supply conduit.
• Tribo charging: This uses the friction of the fluid which is forced through the barrel of the paint gun. It rubs against the side of the barrel and builds up an electrostatic charge.
• Post-atomization charging: The atomized fluid comes into contact with an electrostatic field downstream of the outlet nozzle. The electrostatic field may be created by electrostatic induction or corona, or by one or more electrodes (electrode ring, mesh or grid).