Many guitarists, in their quest to personalize their instruments, often delve into modifications. One such modification involves addressing the aesthetic and functional aspects of guitar pickups. This article delves into the process of wax potting guitar pickups, exploring its purpose, benefits, and potential drawbacks.
Guitarists often seek to personalize their instruments through various modifications. A recent experience highlights this desire: upgrading tuners to locking ones, sanding the neck for a smoother feel, and replacing knobs. A significant challenge arose when attempting to add covers to the pickups, aiming for a specific aesthetic.
After adding covers to the pickups and soldering them to ground, an unexpected issue emerged: the pickups became noticeably microphonic. While there were no feedback problems or tonal changes, a loud, clicky sound was produced whenever the pick accidentally touched the pickup cover.
Microphonics arise from the vibration of metal components within the pickup. Ironically, pickups are designed to capture the vibrations of the strings, but unwanted vibrations from other parts can be problematic, especially under high gain conditions. Metal covers, baseplates, screws, and even the coil itself can contribute to these unwanted vibrations. High gain settings amplify these microphonics, making them more noticeable.
Wax potting is the process of immersing guitar and bass pickups in wax. It is often the last step in the pickup manufacturing process.
Wax potting addresses several key issues:
Reducing Microphonics: Wax potting minimizes unwanted mechanical vibrations within the pickup's components, such as screws, metal spacers, and magnets. By encasing these parts in wax, their movement is dampened, reducing the likelihood of microphonic sounds.
Protecting Against Moisture: Moisture is a significant threat to the health and longevity of guitar pickups. The coil, made from delicate insulated copper wire, is particularly vulnerable to corrosion from humidity, sweat, and other sources. Wax potting acts as a protective barrier, preventing moisture from penetrating the coil and causing damage.
Preventing Corrosion: By sealing the internal components, wax potting helps prevent corrosion, especially of the pole pieces in single-coil pickups. Over time, these pole pieces can develop inner coil pole corrosion (ICPC), which can degrade the pickup's performance.
Insulation Protection and Repair: Waxing helps protect the coil's insulation. In the event of coil damage, the wax can make repairs easier.
The traditional method involves dipping pickups into a pot of hot wax. (Caution: This should only be done with proper procedures due to the extreme danger involved).
Wax: A blend of paraffin and palm wax is commonly used. Paraffin wax is often preferred due to its low melting temperature and ability to penetrate the coil effectively. Lindy Fralin Pickups carefully selects wax to provide the best protection with minimal tonal impact.
Heating Equipment: A double boiler or a temperature-controlled wax melter is used to heat the wax to the appropriate temperature.
Thermometer: A thermometer is essential for monitoring the wax temperature. Maintaining the correct temperature is crucial to avoid damaging the pickup.
Preparation: Ensure the pickup is clean and free of any debris.
Heating the Wax: Heat the wax to a temperature between 150°F and 170°F (65°C and 77°C). It's crucial to maintain a consistent temperature throughout the process.
Submerging the Pickup: Slowly submerge the pickup into the melted wax, ensuring that all parts are fully immersed.
Vacuum Potting (Optional): For more thorough penetration, a vacuum potting system can be used. This involves placing the submerged pickup in a vacuum chamber, which removes air bubbles from the coil and allows the wax to penetrate deeper.
Soaking: Leave the pickup submerged in the wax for 15-30 minutes. This allows the wax to fully penetrate the coil and saturate all the components.
Removing the Pickup: Carefully remove the pickup from the wax, allowing excess wax to drip off.
Cooling: Allow the pickup to cool completely. This can be done at room temperature or by placing the pickup in a cool area.
Cleaning: Once the pickup is cool, clean off any excess wax from the exterior.
The type of wax used is critical. Paraffin wax is often preferred due to its low melting temperature. A low melting temperature is essential to prevent warping plastic parts and damaging the pickup. Some manufacturers did not pot their pickups at the factory. Some of those models are very desirable! Original PAF pickups sound lively and responsive. However, many of these pickups have been rewound.
Historically, some manufacturers, like those producing early Gibson pickups, did not wax pot their pickups. These unpotted pickups are often prized for their lively and responsive tone. However, they are also more susceptible to microphonics and moisture damage. Strat Pickups from the ’70s were dipped in lacquer - a process that worked for years. However, as the lacquer aged, it flaked off and allowed moisture to enter the coil. Furthermore, lacquer does not penetrate the coil - it merely coats the surface.
Gibson-style pickups like the P-90, Humbucker, and Melody Makers originally didn’t have wax-potted coils. The pickups had a higher DC resistance and lower resonant frequency than the Fender Telecaster or Stratocaster style pickup. Also, the Gibson coil was insulated from the pole pieces by means of a fabricated or molded bobbin. The Fender pickup has the magnet wire wound directly to the rod pole pieces.
While wax potting offers numerous benefits, there are some potential drawbacks to consider:
Tone Alteration: Some argue that wax potting can slightly dampen the high-frequency response of the pickup, resulting in a less bright or articulate tone. However, this effect is generally minimal and often outweighed by the benefits of reduced microphonics and increased durability.
Messiness: The wax potting process can be messy, and it's essential to take precautions to protect your work area.
Reversibility: Once a pickup has been wax potted, it can be difficult to undo the process. If you later decide that you prefer the sound of an unpotted pickup, removing the wax can be challenging.
In the initial scenario, the microphonic issue arose after adding covers and performing light wax potting. Several factors could have contributed to this:
Insufficient Wax Penetration: The light wax potting may not have been sufficient to fully dampen the vibrations of the cover.
Air Gaps: Air gaps between the cover and the pickup can create resonant spaces that amplify vibrations.
Inadequate Grounding: Although the covers were soldered to ground, the connection may not have been optimal, leading to unwanted noise.
Thorough Wax Potting: Re-pot the pickups, ensuring that the wax fully penetrates all the spaces between the cover and the pickup.
Vacuum Potting: Consider using a vacuum potting system to ensure maximum wax penetration.
Improved Grounding: Double-check the grounding connection between the cover and the guitar's ground circuit.
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