DIY Hardwood Floor Rescue

Avoid these mistakes when refinishing your hardwood floor.

Of all the home-improvement projects a DIYer might tackle, floor refinishing is one of the least forgiving. At every step, hidden hazards await, destined to appear as blemishes when the job is complete. Worse yet, a serious slipup, such as gouging the floor with a power sander, is impossible to rectify (except by concealing it with carpet or furniture).

On the other hand, few home-improvement projects can transform a room as impressively as a refinished floor. The glow of a flawless finish truly makes the space feel new again. And with professional floor refinishers charging as much as $4 to $5 per square foot (worth every cent, by the way), a homeowner can save a significant sum by taking a DIY approach. With careful planning, you can keep supply and equipment-rental costs to less than $1.50 per square foot.

You can find numerous online sources of information about refinishing floors, most of which are authored by writers who have never done the job or by pros who are settled on their own methods. Though the experienced perspective is of some value, it often does not address the limitations many DIYers face, such as dealing with equipment rental and learning new skills on the job. To help you avert disaster, I’ve identified the most common pitfalls of DIY floor refinishing and offered strategies to counteract them.

1. Choosing the Wrong Sander
Unless you plan to sand many floors during your lifetime (or are a professional floor finisher), you’re best off renting a random-orbital sander. Although they are slower than drum sanders, they do not require a lot of experience and are less likely to permanently damage your floor.

For DIY floor sanding, the best machine is a random-orbital sander (available in the rental department at most home-improvement centers): ideally, one with a large rectangular base, such as the Clarke-American model shown here.

Pads attach to the base, and abrasive sheets attach to the pads. The pads allow the abrasive sheets to come into full contact with the floor.

I have found that random-orbital sanders with large rectangular pads are easiest to use. Avoid rental sanders that have four 6-in.-dia. circular orbital sanders attached to the base of the machine (also available at home centers under the brand U-Sand). These are more difficult to control than the Clarke-American sanders, and because the sanding surface is relatively small, they take longer to remove old finishes. Also, the four-disc units have little or no padding under the discs, so the abrasive does not lie flush with the floor, further reducing the available sanding area and slowing the process.

2. Jeopardizing Your Back
Always recruit a helper when transporting a sander to and from your house, as well as up and down stairs. The equipment is heavy and awkward, so if you do not have help available, ask for assistance at the rental store when loading the sander into your vehicle. Then use ramps to move the machine whenever possible (photo, below).

A ramp can make it easier to move a heavy sander from your vehicle’s trunk to the ground as well as up stairs.

3. Skipping Personal Precautions
Floor refinishing generates large quantities of dust and noxious fumes. Be sure to wear dust masks and hearing protection whenever the sander is on. Remember that dust masks are not effective at blocking fumes, so always wear NIOSH-approved organic vapor respirators when applying stains and finishes. (Some are even equipped with built-in eye protection and splash guards.) I once made the mistake of pulling off my respirator while applying a shellac-base sealer and almost passed out after about 10 minutes of exposure. If you experience headaches or dizziness, move immediately to an area with fresh air.

To further minimize vapors, use low-VOC finishes, and open windows to increase ventilation. Use a fan to exhaust fumes if cross ventilation is not enough. Keep containers closed when not in use, and move application tools outdoors for cleaning as soon as you are done with them. (If you will be using applicators again the next day, you can wrap them tightly in plastic to save cleaning them between coats.)

Avoid getting sealer or polyurethane on your skin. Manufacturers recommend neoprene gloves, but I have found that buying a box of disposable vinyl gloves is more practical. They allow for better finger movement and can be tossed and replaced if they become fouled with stain or poly.

4. Misunderstanding Sanders
Pros have frequent practice using sanders, and they usually do not have to worry about returning equipment to a rental store. DIYers, on the other hand, must work with less skill and within a limited time frame (or incur additional rental fees).

Begin with coarse-grit abrasives that can aggressively remove old finish and penetrate the flooring deep enough to remove surface scratches. However, to avoid damaging the wood, don’t use grits that remove more than 1/16 in. of flooring. (For scratches or gouges deeper than 1/16 in., wood fillers are an option.) Removing the least material possible gives you to the option of refinishing the floors again in the future. Sanding too deeply can cause you to penetrate the top layer of flooring and expose the boards’ tongues and grooves, necessitating a new floor.

Edging sanders are available for rental, but I chose to use my orbital palm sander to save the fee. It did the job just fine.

Make sure your extension cord is long enough and tie it to the sander’s power cord to prevent the plug from disconnecting. Accidental sander switch-offs can mar the floor surface.

With each sanding pass, use finer-grit abrasives until you reach the desired degree of smoothness. For a hardwood floor such as oak, I progress from 60-grit to 80-grit and then 100- or 120-grit. Finally, I use a 120-grit screen to slightly polish the surface so it will receive finishes evenly.

Some professionals prefer to start with more aggressive grits (24- or 36-grit) to speed the removal of old finishes. For novices, that approach can result in uneven surfaces, including depressions and high spots, and hard-to-remove scratches.

Corkscrew markings may be the result of excessive or uneven pressure or starting or stopping the sander while it’s in contact with the floor.

If you use a random-orbital sander (rather than a drum sander), you can move either with or against the wood grain. Just be sure to keep the sander level at all times. Even an orbital sander can “run away” from you and cause deep markings that are difficult to remove. If you use a drum sander, you must always move with the grain.

Whatever type of sander you use, never start or stop it with the abrasive in contact with the floor. Doing so (or applying pressure) with an orbital sander will cause small corkscrew-pattern marks on the floor.

Sand as though you are mowing the lawn. Proceed row by row, overlapping runs by half the sander’s width. You will have to make numerous passes using various grits.

5. Cutting Corners on Corners
After you make vast improvements with a power sander, it’s tempting to ignore corners and low spots. A simple hand scraper can go where the sander can’t. You’ll need one to clean finish out of corners and off of the recesses that often occur at butt joints. Scrapers save a lot of sanding by allowing you to get into small recesses and along board edges without having to remove a lot of extra material with the sander.

A sharp scraper will peel off layers of old finish and wood much like a plane. It comes in especially handy in a corner (above) or at a butt joint between two flooring boards (below).

Sharpen your scraper with a mill bastard file. Follow the manufacturer’s original bevel using a diagonal, slicing stroke.

6. Not Banishing All Dust and Hair
When you’ve finished sanding, remove all dust by first vacuuming and then wiping the sanded areas with a tack cloth or a rag dampened with mineral spirits. Never wipe a sanded floor with a wet or water-dampened rag: It will raise the wood grain and cause blotchiness. Before your final tack wipe of the floor, be sure to vacuum and wipe all moldings, walls, windows and doors with a water-dampened rag to keep dust from settling into the finish.

If you find a stray hair embedded in the dry finish — and if you still have at least one coat to go — lightly sand over the hair with a very fine (320-grit) abrasive. Carefully dig out the hair with a fingernail, if possible. Then sand again with the same very fine abrasive, taking care not to reach the stain layer. Upon re-coating with poly, the mark will all but disappear.

Hair can be a bigger problem than dust. Wear a cap or kerchief while vacuuming and wiping the floor and when applying coats of sealer or polyurethane. Be vigilant as you apply the poly; you’ll likely catch some bits of debris that you missed and be able to remove them before the final coat.

7. Skipping the Sealer
If the wood takes stain unevenly, a coat of sealer will help to ensure even stain coverage. You can test for this by applying stain to an area that will not be visible once furniture is moved back into place. If the stain looks blotchy, even after wiping off excess, remove as much of the test as you can with a mineral-spirits-soaked rag, and sand out the rest after it has dried. Then apply the sealer to the entire floor. Be sure to apply it evenly. Otherwise, “holidays” (skipped areas), stop marks and lap marks may show when you stain. You can use a universal sealer (available at paint stores and home centers) under water- or oil-base polyurethane.

Use a lamb’s-wool (not foam) applicator for applying shellac-base sealers.

Use a brush to cut in around the room’s perimeter.

8. Staining Unevenly
Achieving uniform color, especially over a large expanse, is not as easy as it would seem. I find that the best technique is to apply the stain with an applicator to a small area (about 18 in. x 3 ft.) and rub off all excess with a rag before moving to the next section. Don’t let the leading edge of your job dry or you’ll end up with lap marks (stripes). Oil-base stains stay workable longer than water-base, making it easier to blend sections.

When applying stain (as well as sealer and polyurethane), use standard painting techniques. Always begin your stroke 1 to 2 ft. away from the area you’ve just coated; then brush (or push the applicator) to meet the previously coated area. This will help to ensure even coverage.

Remove excess stain with a rag. The goal is an even tone across the entire floor, although slight variations in tone are acceptable.

If you must pause during a staining job, rub the leading edge vigorously to feather (blend) it with the unstained area. This will make it easier to pick up where you left off without lap marks.

9. Applying Polyurethane Too Thickly
Many pros pour polyurethane along the floor and then spread it with an 18-in. lamb’s-wool applicator. Although this may be the fastest way to lay down a finish, it is more apt to leave pools, drips and lap marks – especially at the hands of a novice. In addition, this approach can be very strenuous, especially during the final smoothing stroke.

Apply polyurethane in 2- or 3-ft.-wide parallel rows, overlapping the previous row. Make smoothing strokes (uninterrupted, continuous runs with the roller using a light, even pressure) after completing each row. The trick is to apply just enough finish so that it will self-level but not so much that it creates a thick film.

A better way for the DIYer is to apply the polyurethane using a high-density foam roller. (In fact, many pros have adopted this method.) The lighter application will be more even and will quickly dry to a glassy-smooth finish. (If you can’t find a 9- or 12-in. foam roller at a home-improvement center, try a specialty paint store or look online.) Use the roller as you would when painting: Back-roll to previously coated areas, and make smoothing strokes after completing each section.

Lightly sand between coats with a very fine (320-grit) paper. A sanding pole will save your knees, but hand-sanding allows you to spot embedded debris. Wipe the sanded surface clean with a tack cloth or a rag dampened with mineral spirits after each sanding.

A foam roller in combination with a brush can be used for cutting in. Apply the finish with a 4-in. roller; then brush it smooth. Do not work too far ahead of yourself. If cut-in areas begin to dry before you can roll them, you’ll end up with lap marks. Note: A brush may be used to coat other areas that are difficult to roll. However, brushing polyurethane requires some finesse. Think of the brush as a jet plane, first making a smooth landing followed by a gradual takeoff. This technique is called “tipping off.” Always brush in the direction of the wood grain. Avoid abruptly setting the brush (“stabbing”), abruptly removing it and over-brushing.

Forgetting an Exit Strategy
Whether you’re applying sealer, stain or polyurethane, be sure to plan your exit to prevent walking on the finish. In general, begin applications along the wall opposite the exit door. Work in parallel rows toward the wall with the door. When you get close, you will have to change your work pattern and work from the end walls toward the door. It might be difficult to make uninterrupted smoothing strokes, so apply a little extra poly and count on its self-leveling properties for a smooth finish.

Renew or Refinish?
If your floor is only moderately worn but has lost the glow of a new finish, you can take a renewal approach. This won’t change the color, but it will extend the floor’s life and save you much of the work of a total refinishing project.

  • First examine your floor to see if it’s a candidate for renewal. Is the finish worn completely away in spots? Are there stains or deep scratches? Does a drop of water soak into the flooring instead of sitting on the surface? If not, the floor finish can be renewed rather than replaced.
  • Next, thoroughly clean the floor to remove all wax, dirt and grime. Use an abrasive pad soaked in mineral spirits, and be sure to wear an organic vapor respirator and ventilate the space.
  • Sand by hand with a pole sander or with a small random-orbital power sander and 100-grit abrasive. Vacuum and remove residue using tack cloths.
  • Apply a sealer coat to help bind the old finish with the new. Follow with two or three coats of water- or oil-base polyurethane, lightly sanding with a very fine (320-grit) abrasive between coats.