Bubbles of polyurethane along the cracks

Q: Our new stained oak floors have developed beads or bubbles polyurethane along the cracks between the boards that flake off. We have a narrow four story townhouse and this occurs most frequently in the center rooms and halls of our house on the middle floor, and then tapers off as you move to the outermost rooms and upper/lower floors.

We have had the floors finished and then re-finished by an independent company and the problem keeps reappearing. Any idea why? Thank you!

A: This problem has happened on only one of my jobs. It was a total surprise. This condition is called poly-balls or poly beads. [Stop polyballs.pdf] gives some information about it. When a coating is applied to a floor and some of the finish seeps between cracks it can take quite a long time to harden, staying soft for months. If humidity in the home rises and the boards expand, it will push this semi-dry finish to the surface. When they dry they can be scraped off with a plastic putty knife and if necessary a buff and re-coat applied to the floor.

Related Q: We have hardwood floors in our kitchen and hall to foyer. We’ve owned this home less than a year. Recently we have had sticky brown (maple syrup like) droplets start appearing in hall and now in certain area of kitchen. What can we do? What is it?

A: Is this on the board edges? If so it is called poly beads. Very unfortunate. Basically is there are gaps between the boards when the floor is finished it will be deprived of fresh air so stays soft. When summer arrives, without good climate control the boards will expand a bit and push the soft polyurethane to the top of the board edge. The only thing you can do is keep wiping it off with a cloth dampened with mineral spirits. When it finally stops weeping you may have to have the floor buffed and re-coated. This condition has only happened to me once in 38 years, but it was once too many times.

Another Related Q: If your floor develops poly beads, is the installer responsible to fix it? Floor finished in March/April, over two months ago. Now we’re ready to move in, in July, and while cleaning I discovered the issue. I don’t want to get into a battle with the contractor. Any direction would be greatly appreciated.

Also, what happens if left as is? They appear to be dry, not wet or squishy. Can more appear as time goes by? I live in the northeast.

A: That is a nasty situation which has happened to me once in 40 years. It is really hard to place blame although I think the person who finished the floors will likely now, as I have, become more educated about the issue and he should be willing to come back and buff and coat the floor. It is actually a good thing that they are now hard. They should be able to be chipped off before re-coating the floor. It is positive that there are no signs of new ones forming. I attach this short article on the subject.