How to Touch Up the Finish on a Window Frame

Remove the window’s old finish, using the appropriate solvent. Use a rag dampened with denatured alcohol to remove a shellac finish. Paint a thick coating of lacquer thinner on the frame to remove lacquer or varnish, or use paint stripper to remove old paint or penetrating oil finish.

Scrape away finish and solvent residue, using a scraper. Use fine-grit sandpaper to remove any remaining bits of finish.

Remove worn stain using sandpaper. Start with coarse sandpaper and work your way up to finer grades. If you are satisfied with the current stain’s color, skip this step.

Buff the bare wood with 0000 steel wool to remove scratches.

Work new stain into the bare wood, using 0000 steel wool, and then wipe the stained area with a clean cloth. Use a stain that matches the stain on the rest of the window frame. If you are painting the windowsill instead, apply paint with a sash brush, starting with the wood next to the glass and working out toward the edge. Overlap the paint onto the glass slightly, and clean away excess with a cloth wrapped around a putty knife. Allow the paint or stain to dry before applying clear finish.

Seal in the paint or stain with your choice of clear finish. Depending on the type of finish, you may spray or paint it on.