HELP. Bubbles in Polyurethane finish

msubobcatJanuary 16, 2008

Hubby and I are refinishing our old wood floor ourselves. The whole house has beautiful old pecan floors, but they were unfinished....just stained. We have sanded and stained and they looked gorgeous. We decided on using Mimwax polyurethane (glossy) for floors, although I was a bit hesitant about having too high a gloss and having scuffs and dust show. Well, after the first coat we noticed that some bubbles appears and some areas looked grainy. The second coat did not improve the situation. Plus, the sheen is REALLY shiny...looks wet. HELP. How can DIY'ers apply oil-based polyurethane without causing these bubbles? Also, I had heard that the third and last coat could be a satin sheen. Because we had used gloss on the first two coats, will this third satin coat be any shinier than if we had used three coats of satin? Sorry for the length of my question. Thanks for your opinions.

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What stain did you use on this floor? How long did the stain dry before your first coat of finish?

There are several things that can cause bubbles in the finish. Stain that has not dried before the first coat of finish can cause bubbles. The stain may feel dry on the surface but still be wet below the surface causing the finish to bubble.

Some brands of finish are known to bubble more than other brands. It could even be your application method causing the problem.

    Bookmark   January 16, 2008 at 7:55PM
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Thanks. I suspect that the stain was not completely dry...that was my first thought when I saw this. You verified my suspicion. We were told to use rollers on the application by a local floor guy, however, we paint-brushed the edges and corners. What is the best way to apply poly? Is our only solution to strip, resand and restain?

    Bookmark   January 17, 2008 at 8:35AM
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Did you shake the can of poly to mix it up good

    Bookmark   January 17, 2008 at 11:34AM
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Hi floorguy:
Yes, we shook up the can of poly well. All I can think is that the bubbles and grainy effect are the result of not waiting long enough for the stain to thoroughly dry before applying the poly and, perhaps, the poly application technique. I hate to go any further on the floor, as I'm afraid we're just adding to the cost of correcting our mistakes. Fortunately, we've only done the living room. We have over 1400 sq ft on the 1st floor alone to refinish. I have a "professional refinisher" coming in next week to look at what we've done. He's already told me via phone that he'll definitely have to start completely over...meaning resanding down to the bare wood. Yikes. But the pecan floors are gorgeous so it's worth the cost, assuming it's done correctly. I keep reading horror stories on this forum about so-called "pros" really messing up a refinish job.

    Bookmark   January 17, 2008 at 2:56PM
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Next time, don't shake the can!!!!!!!!!!!!

See how I tricked you into telling me that little piece of information!!! It is the CSI inspector in me!!

Never shake the can of poly! Always stir really good by hand.

Shaking suspends air in the poly.

    Bookmark   January 18, 2008 at 12:25PM
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Yes your joke was certainly entertaining. We did shake the can I suspect, which probably did contribute to this issue. We are DIY'ers so we certainly don't claim to be experts. Anyway, for any true experts out there, is there anything that can be done to bubbles in the poly other than starting over by sanding down to the wood again? We talked to HD folks and saw a Mimwax rep there. Explained the issue with the over-glossy look and he said that could be changed by applying a "toner" which roughs up the existing poly layer and then apply a satin layer. Don't think that would alleviate the bubbles and grainy effect???

    Bookmark   January 18, 2008 at 3:24PM
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Hi, I have no advice for you, unfortunately, but I'm in a similar situation except that I paid someone to refinish my floors and they were covered in pits from air bubbles and grit. My refinisher came in and put another coat of poly down without sanding it down to the wood. It looks better, but still not the way it should. I hope you get your answer.

    Bookmark   January 18, 2008 at 3:39PM
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Thanks, scramla. When we saw the bubbles after we applied our 1st coat, I was hoping a second coat might alleviate the problem. It didn't. A professional refinisher is coming in next week to look at things. Without seeing the floors, he's already told me he'll have to resand down to the bare wood and start completely over. Of course, he also wants the business and my $$. Are you going to do anthing else to your floors? Thanks again.

    Bookmark   January 18, 2008 at 4:06PM
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Floorguy did trick you and i realize you are a DIY'er but every can has instructions - do not shake, stir slowly to keep from forming air bubbles. I don't thing high gloss even needs stirring, just the satins or semi-glosses. It's going to have to be sanded off now.

You did do right by applying the first coats in a gloss, you then cut the final wear coat to whatever sheen you desire.

Was the stain thoroughly dry before applying the poly?

    Bookmark   January 20, 2008 at 9:02AM
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"Without seeing the floors, he's already told me he'll have to resand down to the bare wood and start completely over. Of course, he also wants the business and my $$."

He wants your business, but he also needs to be able to warranty his work. In order to warranty your floor and his work, he has got to go back to bare wood. What would happen if he comes and screens it and recoats over your work and then the finish you applied peels, causing his work to be messed up?

Would you hold him responsible to fix it on his dime??

    Bookmark   January 20, 2008 at 10:06AM
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Hi , More info from a contractor,i have seen this before, and sometimes the cause is fron usin g a roller,and it impregnates the urethane by lifting the liquid and mixing air to the mix then laying it back down, once it is rolled or foam pad applied it should be brushed slowly to smear,spread, and omiting the suspended air trapped in the poly coat ( Usually ) then washing it letting it dry lightly wipe with paint thinner,never use tac clothes


    Bookmark   June 30, 2011 at 12:36PM
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