Bubbles, dust and debris in finish

Q: I have just had professionals install my new red oak wood floor. There are bubbles on the floor (seems like there is a mix of debris in finish – like dust, splinters and lint as well as just air bubbles in the Poly). They are telling me that this is normal and with time it will go away.

Is this really the case or should they buff and re-apply another coat of poly?

A: I don’t think a home owner should expect a “totally” glass like finish. What I mean by that is, an occasional tiny fleck from a fibre dropping off the applicator should be considered normal in an uncontrolled environment. If you have bubbles and debris I would not consider that normal and it should be buffed and re coated. 1 or 2 bubbles over 300 sq. ft. is not the same as areas of bubbles in front of heat vents, for example. a few isolated individual flecks of debris is not the same as clumps and areas, generally, where there is roughness and debris. Basically, the finish should be smooth with allowance for an occasional, isolated contaminant.

Similar Q: After the 3rd coat of Zar Classic oil based polyurethane on a stained red oak floor, we noticed some lint and hairs that were trapped in the finish coat. Couldn’t have happened in a more noticeable area. Is it possible to spot sand and recoat the problem area?

A: Well it is a coin toss to get an invisible match. Apply painters tape along all edges and ends of boards to be coated. Sand boards with fine abrasive and remove all dust and debris. Apply a thin coat of finish and remove tape immediately.

Related Q: My floor guy has tried 2 times to put Bona poly on my red oak and tiny bubbles appear. What is causing this and can they cause the floor to peel in the future?

A: Bubbles can be caused by a number of things. Finish that isn’t clean. Air movement across the floor while applying the finish. It could even be caused by too much agitation of the finish prior to applying. Water born coatings set up very quickly so it is important not to have any air movement thereby not permitting the finish to flow out and level. I wouldn’t expect this to cause peeling. Peeling occurs because the previous coating was not properly prepared and therefore there is poor bond between coats.

Follow-up Q: Thank you for the information. Since we found several brush bristles in the poly, which he tried to say were hair until we tore one out, I think it wasn’t cleaned properly. How should he clean it after sanding?

A: The floor should first be vacuumed well and the surrounding area also. Then dry wipe the floor with a micro weave mop. I run my finishes through a paint strainer always before using unless it is a new batch.

Follow-up Q: Okay. I will purchase a mop for him to use next week.

Is it possible that he is putting it on with a brush too fast and introducing bubbles? He coated this floor (not the steps), pic attached, in at most 20 minutes. Or does that sound right?

Also, should he use a roller instead of a brush?

A: Application methods depend on the finish being used. If it is a water base coating the recommended method is to cut in the edges with a brush and then pour a puddle down the length of the starting wall several inches out. Then what is called a ‘big foot’ applicator is used. This is an 18″ foam sleeve which slides onto a made for bar. Then he finish is ‘snow plowed’ down the wall length continuously moving the puddle away from the wall until another puddle has to be poured. Generally, water born finishes cannot be rolled. Oil based coating are different. They set up much more slowly. Some can be rolled on and some can’t. I use Poloplaz Primero and Supreme. Both roll on wonderfully with a 1/4″ or 3/8″ pile roller. The only way bubbles would form is if the floor or finish is dirty or air is moving over the floor while applying.

None of these finishes should ever be shaken but only stirred so as not to introduce air into the mix.

Follow up: Thanks for the info.  He put water base finish on by hand with a brush.  We found several brush bristles. I watched him work on his hands and knees.  He is sanding and trying it again this week.  I have come to the conclusion that he installs hardwood floor and has none or little experience refinishing wood floors. 

A: Ah I see. Using a brush on a tiny area with water based finish might work, but a larger area is not possible.  I’m surprised there aren’t multiple other problems too.  The finish sets up very fast and is difficult to keep ahead of it setting up. So, this application method might have contributed to the issue.  This type of finish can’t be agitated much or over worked and there is no working time.  You lay it down fast and get out.