This refers to the sealing of the coils of a pickup in wax. Potting will stabilize the components of a pickup so they will not move relative to each other. Potting eliminates the vibration-induced signals that make a pickup microphonic, and thus prone to feedback. Potting can also protect the inner coils of a pickup from corrosion. Wax is typically used because it works well and is generally inexpensive. Correctly potted pickup coils will have the wax absorbed throughout the coil as well as the surrounding parts (magnets, pole pieces, metal covers). This eliminates any movement of parts within the pickup.