How To Refinish Worn Out Stair Treads

Clean. Vacuum between passes, then wipe down the treads with a tack cloth. This step will ensure that dust and foreign debris like dirt won’t get trapped between the sand paper and treads. Sanding over dust and dirt can create tiny scratches that will show through once the final finish is added.

A belt sander is not recommended here; it is too aggressive for this work. A ½ sheet or ¼ sheet finish sander can be used in lieu of a random orbital, but it is important to move the sander along the grain and not across it. A random orbital sander will make the quickest work of this step.

Sand again. Once you’ve successfully removed the finish and have gotten to bare wood using the 80 grit, repeat the process using 120 grit sand paper.
Clean again. Vacuum the treads thoroughly and then wipe them down again using a tack cloth. Don’t wipe the treads down with a wet rag as this will raise the grain.
Treat the wood. If you wish to change the color of the tread, apply a wood conditioner first, and then an oil-based stain using a cotton cloth. (If you don’t want to stain the wood, skip to Step 7). Be sure all of the previous finish is removed, otherwise the stain will not absorb properly. The wood conditioner will ensure that the stain penetrates the wood evenly. Apply using a brush, rag, or pad. Allow it to sit for about 15 minutes and then remove any excess conditioner using a lint-free cloth.
Stain the treads. Apply the stain liberally using a brush, lint-free cloth or staining pad, and then wipe the tread down using a lint-free cloth to remove any excess stain. Allow the stain to dry for 12 hours. Tip: Do this process at night, or consider doing every-other tread so that the stairs can be used throughout the finishing process.
Apply the Finish. Apply a coat of polyurethane to the treads using a paintbrush. A good quality water-based polyurethane is recommended in lieu of oil-based. Water-based polyurethanes dry faster between coats and are easier to work with. Apply the polyurethane using a good quality brush, starting in one corner and working across the tread, with the grain. Apply the polyurethane slowly and evenly so as to avoid bubbles. Allow the polyurethane to dry for a few hours.
Sand, then repeat two more times. Once the first coat of polyurethane is dry, sand it lightly by hand with 220 grit sand paper. Vacuum and wipe down with a tack cloth. Repeat steps 7 and 8 until you have three coats total. Do not sand after the third coat.

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To refinish stair treads, the old finish will need to be completely sanded off. To do this, Nathan used a variety of tools, including a Rotex 150 multi-mode sander for the majority of the tread, a scraper for the corner of the stairs, and a Sanding Mouse Hook and Loop Sanding Block for around the balusters and the nosing of the tread. The sanding block can be found online. To remove the dust, Nathan used a HEPA Dust Extractor with a brush attachment by Festool and a tack cloth, which can be found at home centers. To apply a new finish, Nathan used a regular paintbrush and a water based polyurethane by Rust-Oleum.