How Charged Powder Particles Coat a Grounded Part

Electrostatic spraying is the core application method for powder coating. It works in the following stages:

1. Charging the Powder

As powder particles pass through the spray gun nozzle, a high-voltage electrode (typically 60–100 kV) gives each particle a negative electrostatic charge, either by corona charging (particles pass through an ion field) or friction / tribo charging (particles rub against a Teflon-lined tube and pick up charge that way).

2. The Charged Cloud Leaves the Gun

The powder exits as a charged cloud rather than a simple stream, since like-charged particles naturally repel each other and spread out.

3. The Grounded Part Acts Like a Magnet

The metal workpiece is electrically grounded, so it’s at a much lower potential than the charged powder. The electric field between the gun and the part pulls the negatively charged particles toward the grounded surface.

4. Wraparound Effect

This is the key advantage over liquid paint: the electric field lines curve around edges and even partially onto the back side of the part, so charged particles get pulled into recesses and corners a straight spray wouldn’t reach.

5. Electrostatic Cling

Once a particle lands, its charge holds it in place against gravity and airflow, which is why the powder stays put even before curing — there is no wet paint to sag or drip.

6. Overspray Recovery

Powder that misses the part is still charged, so much of it can be recovered and reused (typical for booth reclaim systems), unlike liquid overspray.

Summary

The whole trick is basically: charge the powder, ground the part, and let the electric field do the aiming.