White lines in between the long edges of the floor boards

Q: I’m a contractor and just had 4′ walnut flooring installed in a clients home. A few months later, there are white lines in between the long edges of the floor boards in many areas.

I can’t find any answers online. Any input would be appreciated!

A: Ok, I’m going to give it my best guess based on some assumptions. This is site finished. It was finished with a water borne urethane. The floor has shrunk a bit and the finish has stretched and fractured creating these white lines.

Follow-up Q: Your assumptions are correct. I’m guessing the only fix is to resand and refinish the entire floor?? Is this a manufacture issue with the poly?? No one wants to claim any liability for the work and I’m stuck with a lot of finger pointing….

A: Of course nobody wants to accept liability, and everyone wants to find someone to blame! But that doesn’t find a solution. I’m using Poloplaz finishes now and have been for more than a year. Great products and great support! I did pose a question to a Dura Seal rep a number of years back regarding a situation that happened to me even though I did everything properly and there was no indicator that the problem was going to occur. His response was: If you do this work long enough, shit happens!

I don’t know if this could be called a manufacturing issue. It is a simple fact that water borne finishes are more brittle that oil based and don’t stretch as well. I was thinking about the differences between the 2 genres of finish on my drive home today and I have to say, for every good thing that can be said about water borne urethanes, there seems to be a negative. Here is what I mean. They dry and cure much faster than oil based which is good for the home owner. However, the quickness of set up can make them very tricky to apply. They don’t smell bad but that can leave a person thinking they are very safe which they are not, if using a 2 component finish. They dry crystal clear but that can look rather stark on a non stained floor. I am ranting!

I have used these finishes off and on for a few decades but don’t use them often. I don’t consider them as durable as a good solvent based finish though they do have advantages in some situations. I’m not sure if buffing and applying another coat will solve the problem or you will have to start over. My suggestion is either get advice from the company who made the finish or scan the web site at floormasters.com to see if you can find an answer. I know this issue has come up but I don’t recall what was decided to be the fix.

If you do a lot of this I would encourage you to consider Poloplaz products. Primero is excellent. The best oil based polyurethane I’ve ever used. They also have a high end water borne that has the second component/hardener added to the finish. The way it works is the product is shipped at a ph of 8. After it is applied the ph drops and becomes acidic and this activates the cross linker. No handling of nasty chemicals with mixing and no finish waste. I haven’t tried this product, 202 yet, but it sounds promising as far as water borne finishes goes. Another thing, if you have a problem they give good support. I’ve even sent questions to their chief chemist who was gracious enough to reply with a detailed response.

Second Follow-up Q: I did have the material supply rep come out and he said he believes it is WLS or white line syndrome. Have you ever heard of this terminology?? He (rep) has heard/read about it but never actually seen it in the Chicago area in the 30 years he has been in business. I think we will try to determine from the finisher what product was used (I know it was water based) and contact the manufacturer rep for more input. I’d hate to refinished it (including moving all the furniture on the entire 1st floor completely out & back in) just to have it happen again. Thanks for all your input…. I appreciate your time and info.

A: WLS is what my first assumption was. Water borne finish stretches, cracks and appears as white lines. I think your approach at this point is what I would do too. Contact the finish manufacturer and see if you can get some satisfying answers. Good luck on that one.

Related Q: I had new hardwood floors installed, and there are white lines along many edges of each piece of wood (from the urethane). The floor installer and finisher said it was due to the floors being dark and the new standards required for the newer urethanes. He said nothing could be done. It looks awful. Is it true what the installer said or is there a solution to get rid of all the white lines?

A: It sounds more like the boards have shrunk, stretching and then fracturing the finish along the board edges. I would try a buff and re-coat. The finish will have to be screened well before another coat is applied.

Related Q: I had my floors refinished in December. I just noticed white areas forming in the seams of some of the wood pieces. New white areas are forming almost daily. Almost like the polyurethane is coming up from the floor. One of the sticky pads on my kitchen table leg actually pulled the poly right off the floor. What is happening?

A: This doesn’t sound good at all. White lines along board edges can occur when a floor is finished and the finish covers board edges. Then when winter arrives, the heat is turned on and some shrinkage occurs, the finish stretches and breaks. That the bottom of a table leg would pull the finish off the floor tells me there isn’t a good bond between coats. You will need to call the company back who did the work. There may be more going on but I don’t know what finish they used, what procedures were followed or what the condition of the floor was when they started work.