Dampen a sponge with premixed all-purpose cleaner. Wipe the rail with the sponge. Rinse the sponge with plain water and wipe the rail again. Dry the surface with a rag or let it dry naturally.
Apply painter’s tape around the newel post and baluster connections and any other surface that contacts the handrail. If you cannot curve the tape to fit around a shapely rail, tape the area well and trim the excess with a utility knife to conform to the curves.
Lay newspaper or a drop cloth on the stair treads to guard against drips.
Put on a dust mask to cover your mouth and nose.
Attach a sheet of 100-grit sandpaper to a handheld sander. Sand the rail following the grain of the wood until the finish wears away, revealing the bare wood. Work the sandpaper into any fine curves manually. Sand the entire surface again using 220-grit sandpaper to smooth away any roughness.
Sand the rail by hand with a sheet of 320-grit sandpaper until it develops a smooth sheen.
Wipe down the handrail with a tack cloth to completely remove any residual sanding dust.
Check the tape and replace any areas where sanding lifted or moved it.
Open the can of polyurethane varnish and stir it gently with a paint paddle.
Dip a high quality synthetic filament brush into the polyurethane. Brush it onto the rail in long, slow strokes to prevent bubbles. Allow it to dry two hours, or as directed on the product's label.
Sand out any fine bubbles or visible brush marks using the 320-grit sandpaper. Apply a second coat of polyurethane varnish, as before, and allow it to dry thoroughly.
Peel the painter’s tape off the newel posts and balusters. Remove the drop cloths.
Things You Will Need
- All-purpose cleaner
- Tack cloth
- Painter’s tape
- Utility knife
- Drop cloth or newspaper
- Dust mask
- Medium grade (100-grit) sandpaper
- Fine grade (220-grit) sandpaper
- Ultra-fine (320-grit) sandpaper
- Handheld power sander
- Paint paddle
- Water-based polyurethane varnish
- High-quality synthetic fiber brush
- If your handrail is fastened to a wall, tape newspaper to the wall behind the rail and tape off the bracket hardware before applying the varnish.
- If your sanding produces wood that is unevenly colored, apply a coat of gel stain and allow it to dry before applying the polyurethane varnish.