We both love hardwood flooring. Its rich look and low maintenance make it one of the most preferred of floors. However, wood and water don't mix. Thus, hardwood is impractical in bathrooms, laundries and kitchens. Even the finest finished-in-place hardwood eventually will fail in a wet area.
Although refinishing a wood floor is a process that consists of just sanding and painting, it easily can be messed up if care is not taken.
The first step is to empty the room. Not just the furniture - everything. What you don't remove will have to be cleaned inside and out. The dust created during the initial sandings is vast. You will need to dust the entire house once the job is complete. After the room is emptied, tape all cabinet doors shut, as well as all doorways and openings to other parts of the house.
There are two levels of refinishing: going down to bare wood and cutting away all imperfections or lightly screening the finish and adding a couple of touchup coats. Since the former will prepare you for both, that's the process we will tackle here.
You will need to rent a drum sander, an edge sander and a buffer. Expendable supplies such as sandpaper, finish coat, applicators and thinner can be purchased at a hardwood flooring supply center. What you probably won't be able to rent is a toe-kick sander. This is nothing more than an edge sander that fits under the cabinet toe kick. If there are cabinets, make sure to get a good paint scraper and a sanding block. The last inch or so under the toe kick will have to be done by hand.
Normally, a drum sander is used with a 60-grit paper to cut through the existing finish and down into a fresh layer of wood. When the floor has deep imperfections, a-30 grit paper is the first step, then the 60-grit. The sanding process is everything. Thirty- or 36-grit are used to rough-sand, 60- and 80-grit are for medium-sanding and 100-grit (120-grit on parquet) is used for fine-sanding. The grit used will depend on the condition of the floor. For each phase, the sander is run in one direction with a second pass in a direction perpendicular to the first. This is accomplished by pulling the sander into the center of the room from its perimeter. First one side and then the other. Then from one end and then the other. To eliminate cupping, the first pass is done at a 45-degree angle followed by the perpendicular passes. Sanding at a 45-degree angle is a bit more difficult than conventional directions. Sanding in different directions reduces the chance of unevenness. Additionally, the drum sander is held so that only a small amount of wood is removed with each pass. This takes a sensitive but strong grip, patience and a little practice. An edge-sanding should follow each phase of drum-sanding. Each sanding phase is followed by a thorough vacuuming. The sanding/vacuuming process is repeated until the 100-grit step is complete. Immediately after the rough cut, use a hammer and punch to set any nails that have surfaced (shiners).
A coat of filler is troweled onto the entire surface of the floor, filling all gaps and joints. Two coats are applied - one after the rough sanding and a second after the medium. Some floors can be spot-filled, however we like trowel-filling better. The motion of the trowel as it is used to spread the filler reminds us of a concrete mason finishing a new patio. The filler can be water- or lacquer-based. We prefer water-base as it is safer and dries more quickly. Once the filler has completely dried, you can begin the fine-sanding. Here, the drum sander again is used to perform a 100-grit fine-sanding. With the fine-sanding complete, the drum and edge sanders can be returned to the rental company.
Finally, stain or clear finish can be applied. Selective staining can be beautiful. You can stain the perimeter and leave the center area natural, for example. The options are many. Once the stain has dried, the area is vacuumed. Be careful here. Don't tack the stain coat. Doing so will draw the stain out of the wood. Staining is immediately followed by the first coat of finish, which is applied with a cloth applicator. When the first coat is dry, it is screened with an extra fine 180-mesh or 00 steel wool. Don't use steel wool if the finish coat is water as rust can occur. The floor is vacuumed and tacked (a tack cloth is used to get the surface extra clean). Normally, at least three coats are applied. We used five. The more coats, the thicker the finish and the better the protection. Screening is done between coats, as is spot-puttying, to eliminate any remaining flaws.
Three-quarter-inch-thick wood floors can be refinished several times, whereas thinner hardwoods and parquet can be done only a couple of times. Veneered floors can be screened, but sanding is out. Doing so will almost always result in a ruined floor. Even 100-grit sandpaper will cut right through most veneers.
For more information on hardwood floors and hardwood floor refinishing, contact the National Oak Flooring Manufacturer's Association, P.O. Box 3009, Memphis, TN 38173.
