An electrostatic powder coating gun works on the principle of electrostatic charge. Here's a simplified explanation of how it operates: 

Powder Preparation The gun is connected to a system that fluidize the powder coating material, making it easier to be transported and sprayed. This is achieved through a hopper where air is injected to separate the particles and make them flow like a fluid. 

Charging the Powder: As the powder is fed through the gun, it passes by an electrode which imparts a strong electrostatic charge to the powder particles. This is typically achieved through a process corona charging, where a high-voltage power supply creates an electrostatic field and when the particles pass through this field, they pick up a negative charge. 

Spray: The charged powder particles are then sprayed out towards the object to be coated using compressed air. The object is grounded, creating an attractive force between the particles and the object's surface.

Adhesion: The electrostatic charge causes the powder particles to adhere to the object's surface in an even layer. Due to opposite charges attracting, the negatively charged powder particles stick to the grounded object until melted and fused into a uniform coating during the curing process.

Curing: After application, the coated object is placed in a curing oven where the powder is heated and begins to melt, flow, and then cure into a strong, durable finish.

The electrostatic powder coating process allows for efficient use of the powder with minimal waste, as over-sprayed powder can be collected reused. It also contributes to a smooth and even coat, reducing runs or sags in the finish.