Acoustic guitars typically are stained rather than painted. While it is not uncommon for an electric guitarist to customise a guitar with a personalised paint job, it is far less common for an acoustic guitarist to do the same. However, if you want to customise your acoustic guitar, keep the guitar quality in mind.
Trace the back and top sides of the guitar on a white poster board. Cut the guitar shapes out with scissors. Use the poster board guitar model as a prototype. Develop and create the basic design patterns and colours for the guitar.
Remove all the strings from the guitar.
Cover the bridge and pickguard with masking tape to protect them during the painting process. Protect the fretboard and neck with newspaper and tape if opting to paint the pickguard.
Sand the finish of the guitar lightly with a medium-grit sandpaper to remove the glossy finish from the guitar. Sanding allows the paint to adhere better. Wipe the guitar with a tack cloth to remove the sanding dust.
Apply several light coats of an acrylic aerosol primer to the guitar. Hold the nozzle of the spray can 20 cm (8 inches) above the surface of the guitar. Apply the primer evenly and smoothly. Applying the primer in light coats prevents it from running or developing heavy spots. Allow the primer to dry between coats. Lightly sand the guitar with a fine-grit sandpaper after the primer is completely dry.
Paint the guitar with acrylic paint and paint brushes. Copy the customised design from the poster model. Work with one colour at a time. Allow each colour to completely dry before painting the next colour. This prevents the colours from bleeding into each other.
Apply two to three coats of polyurethane. The polyurethane protects the paint and adds a subtle sheen. Polyurethane is available in aerosol form. Follow the same procedure used in applying the primer. Allow each coat to completely dry before applying another coat.
Remove the tape and newspaper from the bridge, pickguard and fretboard.
Painting an acoustic guitar may alter the instrument's sound and decrease its monetary value.