Refinishing Wood Staircase

wood stairs look nice in any house, adding elegance, along with the richness of wood. But wood stairs tend to wear, as the staircase tends to be a high traffic area of the home. Most people just put up with this or cover it with a carpet runner, rather than paying the high price of having someone come in and refinish their staircase professionally. They’re even more likely to have it carpeted, covering up that beautiful wood, just because that is cheaper.

Refinishing a wood staircase yourself isn’t all that hard to do, even if it is time-consuming. It’s the kind of project you can break up into little chunks, working on it bit by bit, in your spare time. While that will leave an unfinished work in process for however many weeks the job takes, that’s not really any worse than having a beat up staircase which needs to be refinished. Better than that, it will show visitors that there’s a project in process to improve the home.

Before starting any staircase refinish project, it’s important to think the project through and decide what the end result is going to look like. Ask the following questions:

  • What color should the stair tread be stained? 
  • Should the step risers be painted or stained? 
  • Is a runner going to be put on the stairs? 
  • Are we ready to invest the time necessary to fully sand down and refinish the stairs or do we want to make the compromise of going with a stain & varnish combination? 
  • Is the stair rail going to be refinished as well? If so, will the spindles be painted or stained?
  • Are there repairs that need to be made as part of this project, such as replacing damaged step tread or repairing the banister? 

With these questions answered, it’s a good idea to select the stain color and buy all the materials needed, before starting. Building centers sometimes run out of stain colors, so it might be necessary to look in more than one place to find sufficient stain for the project. One quart of stain should be enough to do the entire project and then some; but problems could arise by starting with a partial can of stain that’s in the garage and then trying to find more to match it.

Preparing the Stairs

The hardest and most important part of refinishing a wood staircase, like that of refinishing a piece of antique furniture, is removing the old finish and preparing the surface, before applying the new finish. This is also the time consuming part of the project. There will be a great temptation to shortcut this part, but those shortcuts invariably show up as a lower-quality finish.

If there is any carpeting on the stairs, it will need to be removed before the stairs can be prepped. Care should be taken when removing nails, so as to not make the nail holes any larger. This may be unavoidable in cases where ring-shank nails were used, but other nails should pull straight out.

The next step is to determine if the stairs have any wax on them. Many people have waxed wood floors through the years. Checking for wax requires nothing more than dribbling a little water on the stairs. If the water beads up, it indicates the presence of wax, which should be removed, before sanding, as wax tends to gum up sandpaper.

The easiest way to remove wax from the stairs is to scrape them with a carbide paint scraper, the kind that is used to strip off loose and flaking paint from the outside of a home. This will also remove some of the varnish, leaving less for sanding off.

First sanding

The main tool used in removing the varnish is a belt sander, with 36 grit sandpaper or the coarsest grit available. This might seem like a very coarse grit to use but those stair treads are probably oak, which is a very hard wood, so it can take it. The varnish being removed will also tend to gum up the sanding belt, reducing how much of a cut it can take in the stairs. The belt sander should only be used in the direction of the wood’s grain, so edge trip on the open edge of step treads should not be sanded with the belt sander.

While the bulk of the stairs’ surface can be sanded with the belt sander, it can only get so close to the wall, step riser and balusters for the handrail. The areas of the stairs closest to those other surfaces will have to be sanded with a hand sander, quarter-sheet vibratory sander or “mouse” vibratory sander. In all cases, be careful not to damage the adjacent surfaces, digging into them.

How well the varnish needs to be sanded depends in part on the stain that will be applied. If a dark stain will be applied, then any discoloration of the wood near the wall or riser edges can be overlooked, as long as the varnish has been removed. However, if a light colored stain will be used, step treads need to be sanded fully, so that there are no discolored parts left.

Second sanding

Before continuing to sand with an 80 or 100 grit sandpaper, clean off the existing dust. Sandpaper works better when there is no dust available to clog the paper. It’s also a good idea to lightly draw lines across the step treads with a pencil. The pencil lines will indicate which areas of the steps have not already been sanded.

Clean the steps off again when this sanding is complete, being sure to remove all dust. Check for any unevenness in the stair tread by running your hands over the step tread. You’re specifically looking for any places where the edge of the belt sander might have dug into the step treads. Such places need to be sanded again to smooth them out.

If the step risers are to be stained and varnished, they should be sanded, just like the treads. However, if they are going to be painted, they don’t need sanding. The only exception would be if there is damage. In that case, the damage should be puttied and sanded smooth.

repairing Damage

At this point, it’s a good idea to fill any hole and chips in the wood with stainable wood filler. Before doing this, it’s important to realize that the word “stainable” should be taken with a large grain of salt. While these wood putties are more stainable than others, they are not usually as stainable as the wood that they are used to patch. It’s not uncommon for the wood putty to create an area which stains lighter than the original wood.

One alternative to this requires using some sawdust of the same kind of wood that the step tread is made of. Mix that with a small quantity of stain that is going to be used on the staircase and then spread it out on a waterproof surface, allowing it to dry. The stained sawdust can then be mixed with wood glue and used as putty.

The second alternative is to use tinted wood putty. In that case, the putty shouldn’t be applied until after the staircase is stained and the first coat of varnish is applied. Then the putty can be applied, filling hole and chips, before the topcoat of varnish is applied.

An overabundance of wood putty is generally applied, allowing for shrinkage. This should leave the dry and hardened wood putty sticking up above the surface of the wood. It will be sanded flush with the final sanding of the wood.

Final sanding

The final sanding of the stairs should be done with 120 grit sandpaper. Since the purpose of this sanding is to provide a smooth surface for the finish to be applied to, it is better to use some sort of vibratory sander, like a palm sander or mouse sander for this sanding. It is possible for a belt sander to create gouges in wood, even with this grit sandpaper.

Since the main purpose of this sanding is to provide a smooth surface, it is important to check the surface, running your fingertips over it to check it. Pay particular attention to edges, corner and the area around the baluster, if the staircase has an open edge. These areas are the ones which tend to get sanded the least, leaving a surface that’s not as smooth.

Vacuum the stairwell carefully to remove all sawdust, then go back over it with a damp cloth or tack rag to remove any sawdust that has been missed. Any sawdust left behind will end up in the finish where it will be visible.

Finishing the staircase

With the varnish removed, imperfections in the wood filled and the staircase fully sanded, it is ready for finish. This is a two-part process, consisting of staining and varnishing, although the varnishing part can be broken down into two parts as well, that of applying sanding sealer and then applying the varnish itself.

Oil-based stains are usually brushed onto the surface to be stained. While a cheap paintbrush can be used, a china bristle brush is better. Apply the stain evenly, being sure to cover the entire surface. It is likely that some stain will get onto adjacent painted surfaces, while not desirable, it is okay if this happens, as those surfaces will need to be painted after the stair treads are refinished.

stain can be left on wood for a maximum of 15 minutes. Then it needs to be wiped off with lint-free absorbent cloths or paper towels. There are some paper towel type products made for this, which are thicker and stronger than normal paper towels. By and large, they are excellent.

The longer the stain is given to soak into the wood, the darker a color it will produce. It is possible to go back and apply a second coat of stain, if necessary, for areas that did not stain adequately; but this is an iffy proposition, as there is no guarantee that the stain will soak in any better the second time around.

Once the excess stain has been wiped off, the stairs should be left to dry overnight, before varnishing.

The first coat of varnish to apply isn’t varnish, but sanding sealer. While it is possible to use varnish directly over stain, most of that varnish will soak into the wood. Sanding sealer, like primers used underneath paint, is specifically formulated to dry quickly and not soak into the wood as much. This allows it to seal the surface of the wood, so that the varnish will stay on top, rather than soaking in.

Sanding sealer only requires one hour to dry, before applying the first coat of varnish. A polyurethane varnish is recommended for stairs, as it is for floors. Before applying the varnish, lightly hand sand the stair surface with fine 150 to 220 grit sandpaper to catch any bumps made by lingering sawdust. Wipe the surface down with a tack cloth to pick up any dust created by this sanding.

Apply the first coat of varnish, using either a china bristle or foam brush. Care must be taken to ensure that the varnish is applied extremely smoothly, as any drips, runs or heavy brush marks will show in the final finish.

Leave the varnish to dry for 24 hours, avoiding walking on it during this time. If it is essential that anyone in the family go up the stairs during this time, wait until an hour past the time that the varnish is dry to the touch and wear only socks, so that shoes don’t mar the finish.

The second coat and any subsequent coats of varnish can be applied in the same way as the first, at 24 hour intervals. While two coats is normally considered sufficient, adding additional coats will give your staircase more luster and will last longer.

Be sure to repaint the step risers and the trim around the steps once the step treads are refinished. Not only will some of the stain and varnish invariably and up on these surfaces, but if they are not repainted, they will look drab in comparison to the newly refinished stairs.

wooden staircase, wood
Wooden staircase, Sam Amil

Using Stain & Varnish Combinations

In cases where a stain and varnish combination is to be applied, rather than stain and then varnish, much of the sanding and preparation can be avoided. Of course, this depends on how dark the stairs originally were, how dark the stain and varnish combination being applied is, and how uneven the coloration of the stairs is before starting. While a dark stain and varnish can easily cover a lighter wood, the less of a difference there is between the color of the stain and the underlying wood, the less it can hide. If it is close to the same color, it can’t hide much of anything.

The big concern with using stain and varnish combinations is that they have to be applied extremely evenly. Brush marks, especially those made by overlapping brushstrokes, become glaringly obvious, as the finish will be darker because of two thickness of the finish. As the finish dries quickly, finishing one end of a step, and then overlapping that while finishing the middle part of the step will cause this problem.

It is possible to mitigate this problem somewhat by applying multiple coats, but it is best to make sure that every coat is applied evenly and smoothly, rather than trying to make up for mistakes with additional coats. Each coat of finish will make the overall finish darker.

Refinishing Handrails and Balusters

If needed, handrails and balusters can be finished at the same time, although it is usually best to wait until the stairs themselves are finished and then refinish them. The same steps are required for refinishing the handrail and balusters, as mentioned above for the stair treads.

sanding the balusters can be difficult, as they are usually turned wood. The easiest way to sand them is with a sanding sponge, which will conform to the shape of the wood, allowing them to be hand sanded fairly easily. Power sanders should not be used.

As an alternative, the handrail itself can be refinished to match the stairs, while the balusters are painted to match the step risers. This saves a considerable amount of time, since the balusters don’t have to be sanded down to bare wood.

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