Balsa wood is used in modeling because it is lightweight, inexpensive, easy to cut, and easy to work with. However, balsa wood is not easy to paint because it is a spongy material and absorbs the paint. This does not mean that balsa wood shouldn't be painted, but that balsa wood takes a little more work to paint than materials such as plastic or other woods.
Things You'll Need
Use the sandpaper to sand the balsa wood model until it is smooth on all surfaces.
Use a sealer, such as a sanding sealer, to prep the wood for painting. This will help keep the paint from being absorbed by the balsa wood. Allow time for the sealer to dry.
Paint the balsa wood model from the darkest colors to the lightest colors. For example, if the base of your model will be black with some lighter-colored accents, paint the entire model black first, then add the lighter-colored accents on top of the black paint. Allow each coat of paint to dry before adding another.