The short version
- Grit does more damage than anything else. Dry dusting or vacuuming often, with a hard floor setting, protects the finish more than any cleaner.
- Use a damp mop, never a wet one, with a cleaner made for finished wood floors. Water left standing gets into the seams.
- We advise against steam mops, vinegar, oil soaps and polishes that promise to restore shine. Several of them leave residue that stops a new coat of finish from bonding.
- Know your finish. Site applied polyurethane, factory finishes and old waxed floors are cleaned differently.
- In our data at /data/, 138 of 635 places have 35 percent or more of their housing built before 1940, where a waxed or shellacked floor is still a real possibility.
You are cleaning a finish, not wood
A hardwood floor is wood under a clear coating a fraction of a millimeter thick, and cleaning either preserves that coating or wears it away.
Most floors are finished with polyurethane, applied in the house or at the factory. It is a hard film that sits on top of the wood and takes the wear. While it is continuous, spills stay on the surface and dirt wipes off. Where it has worn through, water and dirt go straight into the wood and the wood turns gray.
So the purpose of cleaning is narrow: remove what would scratch the film, remove what would stain it, and add nothing that stays behind. A floor cleaned that way keeps its finish for many years, and when the finish does dull, it can be renewed with a fresh coat instead of a full sanding.
A floor cleaned the wrong way looks fine for a while and then fails in the traffic lanes, usually sooner than the owner expected and often with a residue on it that complicates the repair.
The routine: grit first, then a damp mop
Remove grit dry and often, and wash the floor only occasionally, with a mop that is damp and a cleaner made for finished wood.
Sand and fine grit act like sandpaper under shoes. Dusting with a microfiber pad, or vacuuming with a hard floor head and the beater bar turned off, removes it before it is ground in. In an entry hall or a kitchen that is worth doing every few days. In bedrooms, weekly is plenty.
Washing comes second and less often. Use a cleaner formulated for finished wood floors, sprayed lightly on the floor or the pad, and a flat mop wrung until it is only damp. The floor should dry within a minute or two. If it stays wet longer than that, there is too much liquid on it.
Wipe spills when they happen. Water that sits finds the seams between boards, and the edges of the boards are where a finish is thinnest.
| How often | What to do | Why |
|---|---|---|
| Every few days in busy areas | Dry dust or vacuum with a hard floor head | Grit under shoes scratches the finish more than anything else. |
| Every week or two | Damp mop with a wood floor cleaner | Removes the film of dirt that dusting leaves behind. |
| Right away | Wipe up spills and pet accidents | Standing liquid reaches the seams between boards. |
| Once a season | Check felt pads under furniture and the mats at the doors | Worn pads and missing mats are where deep scratches start. |
| Every few years, when the finish dulls | Have the floor screened and recoated | A new coat renews the finish before wear reaches the wood. |
What to keep off a hardwood floor
Steam, standing water, vinegar, oil soaps, wax on a polyurethane floor and any product that promises to restore shine all shorten the life of the finish or make it harder to recoat.
Steam mops push hot vapor into the seams and under the edges of the finish. Flooring manufacturers and the wood flooring trade consistently advise against them, and the damage shows as cloudy patches and peeling along the board edges.
Vinegar and water is the most repeated home remedy. Vinegar is an acid, and used regularly it dulls a finish. Oil soaps leave a residue that attracts dirt and builds up. Neither ruins a floor in one use. Both do over years.
The products that cause us the most trouble are the polishes and rejuvenators sold to bring back shine. Most are an acrylic coating that sits on top of the finish. It scuffs, it yellows, and it has to be completely removed before a new coat of real finish will bond. When it cannot be removed cleanly, a floor that only needed a recoat needs a full sanding.
If a product promises shine, read the label for the word polish, restorer or rejuvenator. Those are coatings, and they are not cleaners.
Know which finish you have
Site finished polyurethane, factory finished flooring and old waxed or oiled floors each need different care, and you can usually tell them apart in a minute.
A floor finished in the house has a continuous film and flat seams between boards. It takes the routine described above without complication. A factory finished floor has a small bevel at every board edge and a harder coating. Clean it the same way, with extra care not to leave liquid in the bevels, where dirt collects.
An old waxed floor is the exception. It has a soft, low sheen, it marks white when water sits on it, and a fingernail dragged across an out of the way spot may lift a little wax. Wax floors are not damp mopped with ordinary cleaners. They are dusted, buffed and rewaxed, and a polyurethane coat will not bond over them.
Floors finished with penetrating oil or hardwax oil are cleaned with the soap the finish maker specifies and are refreshed with more oil. If you do not know what you have, text us a photo of the floor in daylight and we can usually tell you.
Old houses and old finishes
The older the house, the more likely the floor carries a finish from before polyurethane, or several generations of finish on top of each other.
The dataset we publish at /data/ covers 635 towns and Philadelphia neighborhoods. In 138 of them, 35 percent or more of the housing was built before 1940, and in Philadelphia 40.0 percent of the housing predates that year. Floors of that age were originally finished with shellac or varnish and maintained with paste wax.
Many have since been sanded and coated with polyurethane, and those behave like any modern floor. Some have not. A floor under carpet for fifty years can still have its original shellac and wax, and cleaning it with water turns it cloudy.
This matters most when the floor is due for renewal. Wax contamination is the classic reason a recoat peels, so on an older floor we test adhesion in a small area before recommending a screen and recoat.
Scratches, pets and furniture
Most scratches are prevented with felt pads, doormats and trimmed claws, and those that happen are either in the finish, where a recoat hides them, or in the wood, where it does not.
Felt pads under chair and table legs do more than any cleaning product. They wear out and collect grit, so they are checked and replaced a few times a year. A mat outside and inside each exterior door stops most of the sand that would otherwise be walked across the floor.
Dogs scratch floors with their claws when they turn and stop. Keeping claws trimmed helps. So does a matte or satin sheen, which shows fine scratches far less than gloss does.
To tell what kind of scratch you have, run a fingernail across it. If the nail does not catch, the scratch is in the finish and a recoat will take it out of sight. If it catches, the scratch has cut into the wood, and only sanding goes below it.
Humidity is part of maintenance
Wood shrinks in dry air and swells in humid air, and keeping the indoor humidity steady through the year protects the floor as much as cleaning does.
In a Philadelphia winter, heated indoor air is dry, boards give up moisture and gaps open between them. In summer the boards take it back and the gaps close. That is normal behavior for a solid floor.
The range can be narrowed. A humidifier in winter and air conditioning or a dehumidifier in summer keep the wood from swinging between extremes, which reduces gapping, and in a wide plank floor reduces the chance of cupping.
Gaps that open in winter should not be filled. The filler is crushed and pushed out when the boards swell again in July.
When cleaning is no longer enough
When the finish is dull and scratched but unbroken, the floor needs a screen and recoat, and when wear has reached gray or bare wood, it needs a full refinish.
The test takes a minute. Find the path people walk most, usually from the door to the kitchen, and look along it toward a window so the light skims the surface. A dull lane with fine scratches and an even color is worn finish. A lane that has turned gray or dark is worn wood.
Worn finish is renewed by abrading the surface lightly and applying a new coat. No wood is removed, the rooms are back in use quickly, and the floor keeps every sanding it has left. Done every several years, it can put off a full sanding indefinitely.
Worn wood has to be sanded. A new coat over gray wood seals the gray in. If you are not sure which you have, send a photo taken in that skimming light and we will tell you, and if it only needs a recoat we will say so.
A recoat done a year before the finish wears through is the smallest job in flooring. The most common regret is waiting one year too long.
