Most modern guitar pickups are potted to prevent microphonics. This can be done with wax or lacquer. Wax is my preferred method for potting pickups as it is easier to work with and penetrates the coil better, but many vintage pickups from Fender and other brands are potted in lacquer. Potting in wax also allows you to pot pickups with the cover attached, potting in lacquer should only be done with the cover removed. By dipping a pickup in wax or lacquer and letting it dry, you are creating a hard casing that holds the individual parts and winds together.
I use a process incorporating lacquer and wax on my Fender-style exposed-pole pickups. Potting the bobbins in Lacquer insulates the magnetic poles from the winds, this way a short is prevented if the coating on the winds is thin or starts to corrode. Once the pickup is completed, it is dipped in wax to prevent microphonics.