When possible, finish the trim before installing it. This saves a lot of fussy work later. The inevitable dings and nicks in the finished pieces are easy to touch up after they’re set in place.

Whether you do your finishing before installation or after, proper preparation is key. If you plan to stain the trim, avoid exposed end grain in your trim work. It’s difficult to keep the end grain from absorbing a lot of color, which looks unattractive. It will look better if you cut and fit returns instead.

1. After the wall patching compound or wood putty has dried, sand carefully with 120-grit paper. Start by leveling the filled areas and then sand the entire surface. Use a damp rag or tack cloth to wipe off the sanding dust.

2. For a painted surface, before or after priming but before the final painting, fill all gaps with painter’s caulk. For a stained and clear-finished surface, apply clear or tinted silicone-based caulk after staining and clear finishing.

Clear finishes
For clear-finished mouldings, start by sanding them smooth; if you’re staining the trim, apply one or more coats. If you’re using water-based stain, you may need to sand with 220-grit paper before finishing to knock down any grain raised by the water. Top-coat with a clear finish for protection.