How to Stain Hardwood Floors: A Step-by-Step Guide

Sanding removes varnish, stains, and scratches on the floor. Before you sand, scrub the floor with a wax remover to prevent buildup and extend the life of your sandpaper. Let the wax remover dry before sanding. 

Use a belt sander to remove the top layer of the floor (about 1/16 to 1/8 inch deep). Start with 50- to 80-grit sandpaper for the first sanding. On the second pass over the floor, choose a grit between 80 and 120. On the final pass over the floor, use a grit between 120 and 150 to smooth out the wood’s surface. 

Run the machine with the wood grain to prevent creating a fuzzy surface that you’ll have to re-sand. Use an edge sander to get the wood near the baseboards and in the entryways. 

If you’re working with old floors, your goal is to remove any products from the wood’s surface. If you’re working with a new hardwood floor, your goal is to create a uniform surface before you apply the stain.

After you’ve created vast amounts of dust and debris during the sanding process, remove every bit of it from the room before you apply stain. This includes wiping down the walls, ceilings, and top edges of trim work that often collect dust particles while you sand. 

Even the smallest speck of dust will mar the finish of a completed staining project, so you’ll also want to take tack cloths to the entire floor after you’ve vacuumed and dusted to create an ultra-clean surface. You can also use a damp (not wet) cloth as an extra precaution to wipe down the floor and pick up every speck of dust. If you do, let the floor dry completely before applying the stain.

Test the stain in a small, inconspicuous corner if you haven’t already. Starting in a corner, pour, brush, or apply roll-on liquid stain following the grain of the hardwood floors. Work from corner to corner so that you keep a wet edge. Plan to do the whole room at once to prevent lapping. 

If you’re applying stain to a raw wood floor, let it soak for a minute or two, then wipe the entire floor down with the rags to remove any excess stain that hasn't been absorbed. The goal is to create a visually appealing base coat, so always take a step back after each section to ensure there aren’t flaws.

Your soaked rags should be treated as a fire hazard once you’ve used them for staining. The volatile compounds in traditional stains can spontaneously combust, so it’s important to keep close track of where you discard them. Soak the used rags in water, seal them up in a plastic garbage bag, and dispose of them in an outside container.

Let the stain dry completely. Humidity levels and room temperature can affect drying times. However, 24 hours is sufficient in average conditions in most cases, but follow the directions on the stain’s packaging. 

Do not walk on the floor while it’s drying. You want to keep the floors clean and unmarred while the floor dries.

The location of the floor influences whether you’ll want to use a varnish or finish. Varnish creates a highly water-resistant surface, making it more common in outdoor spaces or rooms that will get a lot of traffic from the outdoors. However, it’s prone to cracking if not applied correctly. Finishes offer a more refined look thanks to their transparency, and they come in appearances that range from glossy to flat for a wider variety of looks. 

Varnishing 

Once the stain has cured, remove your shoes to prevent scuffing. Grab a natural bristle paintbrush and apply the first coat in a thin, even layer. Go with the grain, but do not drag your brush back and forth. Let the first layer completely dry.

Use sandpaper, 400- or 600-grit works fine, to lightly sand the floor. Then, apply another thin coat of varnish. Repeat these steps until you have a third or fourth coat on the entire room and are happy with the result.

Finishing 

A polyurethane finish can give the floor a brilliant shine, with both gloss and semi-gloss options available. Using a natural bristle brush, water-based applicator, or lamb’s wool roller, start in the corner furthest from the door. Follow the grain of the wood as you apply the finish and work your way toward the door. Always maintain a wet edge to prevent lap marks.

Let the finish dry for several hours before lightly sanding it with a 220-grit sandpaper. The sanding removes any imperfections or surface bubbles. Clean the floor, then apply a second coat.

Let the finish cure for two to three days before walking on or moving furniture on the floor.