How to Stain Wood Fillers
- 1). Stain the wood surface as you would normally. Allow the surface to dry, then apply a single coat of polyurethane finish. Allow the finish to dry before adding wood filler.
- 2). Sand the entire wood surface, moving along the grain.
- 3). Mix wood filler with the same stain you used to stain the wood until the filler matches the color of the wood exactly.
- 4). Pack wood filler into holes and cracks, using a brush. Brush the filler across the grain, then along the grain. Allow the filler to dry before applying two final finish coats of polyurethane to the entire wood surface.
Source...