How to Sand and Varnish Hardwood Floors

The finish on hardwood floors consists of two parts: stain that soaks into the wood and gloss that sits on top of it. Whether you're finishing a floor for the first time or refinishing it, you have to sand off the top layer of the wood to prepare it for staining. A drum sander is the easiest way to do this. You can rent one from a home improvement store. Polyurethane is the most common floor gloss, but some people prefer the softer shine of varnish.

Things You'll Need

• Drum sander
• Sandpaper for the sander (heavy, medium and light grit)
• Vacuum cleaner with floor attachment
• Tackcloths
• Floor stain
• Paintbrushes
• Rags
• Polyurethane
• Floor gloss applicator
• Fine sandpaper

Instructions

1. Set up the drum sander with the heaviest-grit sandpaper. Run it over the floor at a direction diagonal to the boards, so it takes off the top layer of finish and part of the top layer of wood. Sand the whole floor in overlapping courses.

2. Pick up the dust with a vacuum and floor attachment.

3. Reload the sander with medium-grit sandpaper. Sand the floor again, but move the sander in the opposite diagonal direction from before. Take up all remaining finish, so the floor is bare wood. Vacuum.

4. Load the sander with light-abrasion sandpaper. Sand in the direction of the boards until the surface is smooth and flat. Vacuum. Go over the surface with tackcloths to pick up any residual dust.

5. Apply wood stain to the floor with a brush. Work in sections of 4 to 6 square feet, brushing the stain on thickly so it pools, letting it sit on the surface for a minute, then wiping up the excess stain with rags. Stain the whole floor. Let the stain dry for a full 24 hours.

6. Pour varnish on the floor in the corner farthest from the door of the room, making a puddle the size of your floor gloss applicator. Set the applicator in the puddle. Pull it slowly backward, in the direction of the boards. Pour more varnish as needed and repeat. Varnish the whole floor.

7. Let the varnish dry for 12 hours. Lightly sand it by hand with fine sandpaper, dulling the shine so the next coat will adhere. Wipe up the dust with tackcloths.

8. Apply a second coat of varnish in the same manner as the first. Let it dry, lightly sand it and apply a third layer. Let it set for a full day.

Tips & Warnings

• Wear a particle mask when sanding.

References

• Flooring Knowledge: Refinishing Hardwood