Oil-Based Stain With Polyurethane Blistering On White Oak Floor


white oak floor, stain and two poly. poly is starting to blister at board edges and ends. also, painter’s blue tape would pull up finish after being down for ten minutes. what is causing this?


Dear Frank

You are a man of few words, but I do believe I know the problem. If it was a new floor, the fact that the wood white oak wouldn’t have affected the results, unless it was a water based stain. So, I’m surmising that you used an oil based stain, and let it dry according to the directions on the can.

But the trouble with most can labels directions is that they may not take into consideration that you are staining a floor. A wood stain that will dry in 24 hours on a table, can take from 24-72 hours to dry on a floor. The large area, and the fact that floor will hold a lot of stain, makes these areas dry quite slowly.

Now, if the stain wasn’t fully dry the still wet oils on the floor would not allow the next coat of poly stick to it. And there might have been a clue to this if the poly had bubbled or pitted a little bit. If you did not scuff sand this coat the last coat would have also not adhered well, but may have also looked OK. This is especially true for these newer fast dry polyurethanes.

The best way to determine which coating is not sticking, is the finish adhesion test. Using a razor, cross hatch the finish down to the bare wood, after it has cured for 30 days (to be fair). Apply a piece of duct tape and rip it off. If more that 20% of the finish is peeled off you have a failed finish. But, look more closely. Is it peeled down to the stain or just the last coat. Chances are it will lift to the stain.

So, I hate to be the one to tell you this, but in the case finish that didn’t stick to the stain, you will have to sand or chemically strip the floor to the bare wood and start all over. This time use a professional quality fast dry pigmented wiping stain. I use a locally made stain that the can label says will dry in one hour. But I let it dry overnight, and for 20 years I have not had one peeled finish.

But if you discover it was only the last coat of poly that didn’t stick to the first coat, and after doing the adhesion test you find that most areas are OK. You could TRY to screen off most of this peeling last coat. And recoat again. But this is risky. You will have to use a 100 grit screen on a buffing machine, and do this fairly aggressively. The trouble is that some of the stain may come off in the process, and you will have to do a lot of touch ups. This may prove to be so difficult that it may be better to sand or strip the floor all over again, to avoid further problems.

Most professionals do not use fast dry polys. And we always allow for long dry times between coats, and screen (scuff sand) between coats of poly. In fact I have written the difinitive article on exactly how to apply oil modified polyurethane without the bubbles or any adhesion problems. It’s not easy or quick (8 pages) but my methods have proven themselves over 20 years of hard use. I’m sitting on one of my 20 year old poly finishes now. I will tell you even what brand of poly I use right now. The Fabulon Heavy Duty poly satin.

And in about a month or so we will post articles on how to sand a floor to ready it for the stain, avoiding machine marks. And yet another article on the 4 different varieties if stain I use to color different species of wood. You see this is not a 1-2-3 big orange box store web site. I will tell you all that I know, if you care to learn.

If you have followed the direction on the can label to the tee, and have at least one witness to attest to this fact, you may have a strong case against the manufacturer. In some cases some finish makers have paid for the resanding of the wood floor by a professional, and have refunded the cost of the finish. But you will have to be persistent. If it was new wood, there will not have been any contaminants in the wood so this would not have been a limiting factor. If this was an old floor however, and you did not sand it well enough to the bare clean wood, well this is another matter altogether. But the solution is the same for all cases, sand to the bare wood and do the job again.

As always your Most humble servant, Joseph, the Wood Floor Doctor.