A few tips can result in a quality finish for swamp ash guitar bodies.
Electric guitar bodies are available in many different woods, which offer a wide array of sounds for the guitar builder. Body woods are selected for their sonic qualities, physical properties and aesthetics. Many Fender-style guitars such as the Telecaster and Stratocaster have swamp ash bodies, as did Eddie Van Halen's first custom guitar. Harvested from the bottom of ash tree trunks in marshlands, swamp ash features a punchy sound, solid yet lightweight feel and semi-tight wood grain, making opaque or translucent finishes easy to apply.
Body Preparation
Preparation is key to a finish on any guitar body. Repair to the body must be complete before finish preparation can begin. Glue and clamp any cracks or breaks, and sand any dented or raised areas flat to ensure a smooth surface. Swamp ash is a moderately hard wood, so care must be taken to not oversand flat areas. Power sanders may have excessive power and too little control, so many luthiers choose to sand the entire body by hand.
Filling the Grain
Swamp ash has a medium grain that must be filled for a mirror-like finish. Grain filler, a nitrocellulose compound available at woodworking shops, is applied by hand to the guitar's body with a cloth such as an old T-shirt. Wipe the filler onto the body across the grain. After an hour, repeat this process and allow it to dry overnight before sanding with 220-grit sandpaper.
Sand and Sealer
A nitrocellulose sand and sealer compound should now be applied to provide a level and steady base for the final finish. Brush the first coat onto the body with a quality brush to fill any small scrapes remaining from sanding and let dry for an hour. Apply a second coat and allow it to dry overnight. Sand the body again with 220-grit sandpaper followed by 320-grit sandpaper to remove any shiny spots.
Primer
Color finishes require a white-pigmented primer for even color application. Spray two coats onto the body and allow to dry overnight. Smooth any roughness with 220-grit followed by 320-grit sandpaper.
Spraying Color
Spray colors in multiple thin coats to ensure even coverage. Too much paint will choke the wood's sound. Spray enough coats to achieve the desired color saturation, then spray two more coats to ensure even coverage. Always hang the body by the neck attachment holes for easy access all around the body.
Spraying Finish
Wipe the dried body with a tack cloth to remove any dust, then spray thin coats of clear finish until the body is well covered. When the desired coat thickness has been achieved, allow to dry for two days before wet sanding and polishing with 600-grit sandpaper to complete the finish.
