Faraday cage effect defines a condition that occurs when parts are coated that have recesses, inside corners, channels, or protrusions on their surfaces. The Faraday cage is the area of the part where the external electrical field does not penetrate. Powder coating of recessed areas is often complicated.
For the successful coating of Faraday areas, the following conditions must be met: powder has to be well charged, airflow must be sufficient to deliver the powder inside a recess but not excessive to preclude powder deposition, and the external electric field must be controlled to reduce the "push" for powder particles to deposit on the edges of a Faraday cage. Because most Faraday areas involve some type of "pocket " areas, it is important that the method for direction the powder flow in allows for displacement of the air in the pocket area to allow penetration.