Sanding a wood floor to refinish it is not too difficult, but it is dusty, noisy and time-consuming.
A floor thickly covered with paint should be chemically stripped first, to reduce the amount of sanding necessary.
In some communities, homeowners must hire a professional to remove paint applied before 1977 because it may contain hazardous amounts of lead. Contact the local health department for advice and to have paint tested for lead.
Also consider professional treatment if the floor is ornately patterned, or if the floorboards are less than 5/16 inch thick.
Before any work begins, carefully prepare the floor and the room by removing all items and sealing all openings to the rest of the house, to prevent dust from escaping. Cover cabinets and appliances that cannot be removed; extinguish stove pilots and leave windows and outside doors open for ventilation.
Scrupulously inspect the floor for protruding items, especially nailheads. Use a hammer and nail set to drive these at least an eighth of an inch below the surface. Remove items like staples and old carpet tacks;
refasten loose floorboards and repair large cracks or splinters with glue. Vacuum the floor.
The essentials
To sand a floor, you will need a drum sander and an edger (two power tools available from rental centers), goggles, ear protectors and a dust mask. A drum sander resembles a large upright vacuum cleaner. Its main components are the drum, a horizontal cylinder around which sheets of sandpaper are attached and an electric motor that spins the drum at high speed over the floor.
Be sure the sander operates on ordinary household current (120 volts)
unless a 220-volt outlet, such as for a clothes dryer, is conveniently located. The easiest models to load and use have a slotted drum or take belts of sandpaper rather than sheets.
An edger is a smaller machine for sanding hard-to-reach areas. It uses disks of sandpaper rather than sheets or belts.
Sandpaper is usually supplied with rental tools. Customarily, unused sandpaper is returnable. Have the salesclerk demonstrate the operation of both sanders and how to change sandpaper.
3-pronged assault
Most floors are sanded in three stages. First, a coarse grade of sandpaper is used to remove the finish (20-grit for a painted floor, 36- or 50-grit for a clear-finished floor). Then a medium grade (80-grit) and a fine grade (100-grit) are used to remove scratches. Sometimes more than one sanding with coarse-grade paper is necessary before moving to the finer grades.
When sanding a clear-finished floor, begin with 50-grit sandpaper unless the finish is very thick. If the sandpaper clogs quickly, switch to 36- grit. If the 50-grit paper performs adequately-removing the finish down to bare wood-the second sanding with 80-grit sandpaper can sometimes be omitted. On parquet floors, begin with 80-grit paper. If it removes the finish, follow this with 100-grit paper to complete the job. If the 80-grit sandpaper clogs, switch to 50-grit paper and perform all three sandings.
Begin each stage of sanding with the drum sander. Place it against a wall parallel to the floorboards so you can sand them lengthwise. Leave at least six feet of space behind the sander for maneuvering it. (It is a good idea to mark this point with a line of chalk across the floorboards to the opposite wall.)
On a parquet floor, the first sanding should be at a 45-degree angle to the room`s length. The next sanding should be at a 45-degree angle across the first, and the last sanding should be parallel to the room`s length.
Careful now
Operating a drum sander without gouging the floor is tricky. The cardinal rule is to never let the sander remain stationary with the drum touching the floor, and never start or stop the motor in this position.
Begin with the drum raised and the cord either draped around your shoulders so that you do not run over it, or clipped to your belt. Be sure the dust bag on the sander is out of the way.
Turn on the motor. When it reaches full speed, gently lower the drum while pushing the sander forward.
Take small, slow steps to prevent the sander from moving forward too fast. Keep the tool moving at an even rate and in a straight line.
Raise the drum before the sander strikes the wall at the end of the floorboards. Begin walking backward, and lower the drum again as you do.
Draw the sander over the path it has just taken. When you return to the starting point, raise the drum just as the sander crosses over it.
Maneuver the sander to the side so that the drum overlaps about half of the previous pass. Then begin the second pass, guiding the sander as before.
Continue across the room until you reach the wall opposite the starting point. Then turn the sander around and sand the remaining part of the room on the other side of the chalked line.
Renew the sandpaper when it dulls, tears or clogs. Empty the dust bag when it fills more than halfway.
Use the edger in areas missed by the drum sander. Move the tool parallel to the floorboards or in small, overlapping clockwise circles. Do not press down or you will gouge the floor; the weight of the tool supplies sufficient pressure.
Finishing touches
After rough sanding, vacuum the floor and fill any cracks or holes with wood putty made by mixing sanding dust and lacquer to the desired consistency. Wear a painter`s respirator when working with lacquer.
After the final sanding, use a hook-style hand scraper to scrape areas missed by the edger. Then smooth the scraped surface by hand-sanding.
Before applying finish, rent an electric floor polisher and buff the floor with a 120-grit abrasive screen.
