Water-Based Urethane And Lacquer Sealant Create Wear Marks



My refinished wood floors are developing some unusual wear spots and a friend thought I should make sure there is not some unusual problem (such as a fungus or rot).

The floors are the original red oak flooring (house is 54 years old).  I had the floors refinished in fall 2005 prior to moving in (previous owners had pulled up carpeting and then stained the floors but did not add a finish).  The floor refinishing company sanded, applied one coat of stain, one coat of sealer, and two coats of high durability water-based polyurethane finish (Eon 70).

Within 1 1/2 years, I noticed some wear in certain higher traffic areas but these only occurred in the part of the wood planks where the wood ‘rings’ or grain were located-basically ridges developed in the wood grain areas which appear to be bare wood.  AFter 3 years, several of these ‘bare-wood ridge’ areas have developed–mostly in higher traffic areas.

Do these bare wood ridge areas indicate some sort of problem with the wood itself?  Or do I simply need to have the floors refinished in these spots?  If the latter, could I do some spot refinishing, or should I get another professional company.

In thinking about this further, I realized that the term “ridge” might not be the best description, since the bare wood  areas don’t stick up above the floor.  “Groove” is probably a better word.


Dear Anne,

There is no fungus on your floors.  This is not an unusual problem.  However, it will require some work.  In a nutshell, your floors were done very poorly and this is why they unfortunately have this appearance right now.

There is a very big difference between water-based and oil-based polyurethane.  I’m not sure if the issue of water-based finishes is their hardness, but their whiteness. The water-based industry goes to great lengths to point out that the oil-based polyurethane turns yellow. Well the water-based finishes whiten in time, and this may lead further down the line to the cracking you speak of (your floor finish wearing off).  I have heard from art restorers that water based varnishes have not yet come of age, because the dried film still has the emulsifiers in it. These are a detergent like chemicals that allow the mixing of the oil and water in these finishes. They are large molecules and in time may migrate together as the finish continues to cross-link.

That may happen in as little as 1.5 years in your case (but usually it takes about 5 years to see this) and the floor finish will turn so opaque that the wood grain will be obscured. And I suspect that in time also, with some UV deterioration in strong sunlight window exposure, this process will be speeded up. And then the cracking begins.

Another problem with your floor is the lacquer sealant.  Lacquer seal is a major source of fires.  Most lacquer finishes and their poorer cousins the lacquer sealers are made from nitrocellulose (which is basically cotton and wood fibers dissolved in acids) alkyd resins and plasticizers. But it’s the addition of lacquer thinner that makes this stuff so fast drying and explosive.  It is quite a dangerous choice to use a lacquer sealer.

Another important thing to know is that using water-based polyurethane and lacquer on the same floor is not a good idea.  They basically serve the same function.  One will usually not stick to the next.  It looks like the lacquer has also peeled off.

Are your wood floors ok?  Absolutely.  I know you probably want to refinish only the worn areas.  This is a very bad idea.  For one, the floor will not look even.  You will be sanding off certain parts and starting over and leaving other areas the way they are.  It is not like painting a wall, where touch-ups are painlessly easy.  It is very different.

What I recommend, and I know you are not going to like this but it is going to ensure a gorgeous looking floor: Redo the entire floor.  You will need to sand down the entire floor and start again.  Please get your floor contractor to the following:

Apply one thinned coat of polyurethane. Wait 1-2 days for it to dry at 21 C. Scuff sand the floor smooth, vacuum and tack rag with varsol. Allow solvent to dry. Apply a heavy coat.  And repeat the same thing for the last coat.  Always brush the finish on with a good quality 4″ bristle brush.  Make sure that he uses a good quality brush.  It’s not rocket science but you may have to ask quite a few contractors before you find one willing to do such a thorough job. The guy you had took the easy and quickest way to do your floors.  Ideally, you also want to have three coats of stain to have a nice, even looking floor.  I highly recommend hiring a new flooring contractor.  If you want great durability, get your floor guy to use a water based finishes called Dura Seal 1000 finish.


Dear Wood Floor Doctor,

Thanks for your prompt reply. I’m glad to hear that there is nothing wrong with the wood in my floors. As you say, it’s not the best news to learn that I need another total refinish job, given how recently this was done and that the bill was expensive. Next time I will get a different company and stay away from water-based polyurethane (which had been promoted to me as being more environmentally friendly–but without mentioning the durability problem).

Unfortunately in the current economy I can’t afford a new refinish job in the near future. Is there anything I can do to temporarily protect the bare wood spots? Or should I not worry about them?




Dear Anne,

Your floors will probably peel more over time. However, if you want to wait and not spend the money right away, it isn’t a problem. Please make sure that no one wears shoes at all on your floors, especially not stiletto heals. Shoes on all wood floors will wear the finish very quickly. If stiletto heals are worn on your floors, you will more than likely void your warranty just like that. It is a really easy thing not to do.

You say that you thought that a water-based polyurethane is more environmentally friendly. It surely is not. Water-based only sounds better. Most water-based finishes contain azridine catalyst or hardener. This stuff is a confirmed carcinogen, and when absorbed through the skin ( it easily does) causes tumors, and prolonged exposure to this seems to cause skin reactions, and allergies.

In the future, when you decide to redo your floors, PLEASE use oil-modified polyurethane if you want to have a long-lasting, durable floor.

Best of luck!

The Wood Floor Doctor Team