Final buff too aggressive

Q: We recently had our floors refinished by a professional. First he weaved in some new floor with our existing floor, where a few walls came out. Then he sanded three times and applied stain. On top of that he applied 2 coats of WS 2K Supra by Lobadur for the water based finish. The floor looked quite good and even but still somewhat raw, however we did chose a matte finish so this may be the reason for that. And then the final buff.

My concern is this week (3 mo after previous process) he returned at the end of our reno to buff using drum and apply a third coat of finish. After he did this all of the new wood stain was removed along the edges and there are chatter marks, waves, uneven stain, and the perimeter of the rooms and fireplace hearth are all darker than the rest of the floor.

He told me this was because the contractor allowed the house to get too cold in between the two processes and the flooring cupped from the temperature changes. Is this is sole reason for all of these issues? To me the technique appeared poor over all the floors, new and old and in every room and the perimeter issue seem to be because the edges of room were not buffed. He said they used 220 grit on the drum. It looked like they sanded far too aggressively and used poor technique to me. Thoughts? I do know his son was the one to do the final buff and finish while the first go round it was himself.

A: This actually started out sounding like a good news story. He sanded with 3 different grits, stained and applied 2 coats of cross linked water born finish. You need 3 coats because water born coatings are not high build. I was then thinking he must have backed off until other work was completed, which is indeed what took place. Most people don’t like matte finish, though I wish it was everyone’s choice. It tends to hide defects.

But this really went sideways when his son came back to buff and apply the final coat of finish. You don’t use a drum sander to do that sort of preparation. You would use a polisher and some type of fine abrasive. Norton Abrasives has even invented a series of abrasive pads which will scuff the coating without leaving visible scratches or swirl marks that can occasionally become an issue. Why he did not do this is just bizarre.

Did the floor cup after he finished and went away? This can create a big issue if you have to buff for another coat. It still doesn’t excuse him using a floor sanding machine to abrade the coating. Cupping is caused by moisture imbalance with the moisture coming from beneath the floor. Problems can occur in a closed building in winter without any heat. The sun comes across the sky during the day and warms the air and moisture holding capacity of that air and then in the evening as it gets cold that warm, moist air can condensate on various surfaces. I rather doubt that was the case here. Guys are working in there. They aren’t working in freezing cold. Aren’t you living in the building?

I suspect a lot of these marks may have been in the original job but the matte finish hid them. But, no matter what, the person who came back to buff and apply the final coat didn’t know really what he was doing. And if the floor was cupped, he should have pointed out the issue to you before proceeding. This is going to have to be done again from the start.

He could have used one of these pads on a polisher:

Follow-up: Thank you so much for all your helpful information! I may have used the wrong terminology, I believe what he used maybe was not a drum sander but a floor buffing machine? It was circular I think and he said he used 220 grit which may be similar to the Norton link that you sent me.

So in that case, could the sanding still have been done too aggressively with the wrong technique? Or do you think the issue is more that initially there were problems that were not visible until final buff and finish coat? To me, the fact that the flooring is darker around perimeter and very uneven in some places with the chatter marks, etc., made it appeared that whatever they used this most recent visit may have removed too much stain? Not sure if that’s possible with that grit.

Also one other quick question, there was what appeared to be dry wall dust trapped in grain underneath the finish in many places. A whitish gray haze look. Do you think this is due to improper cleaning (he said they vacuumed really well) or perhaps that he did not use primer/sealer below the first coats of finish?

This has been so helpful. I don’t want to call him out on issues without first understanding what may have happened. Trying to work together with him to get it fixed.

A: 220 Grit screens are very fine. I wouldn’t expect it to cut through the finish and into the stain also. At least not if he was working promptly and carefully, not leaving the polisher sit in one spot. If the floor was indeed cupped, then all bets are off. It sounds like the guys that did the mudding and sanding of the dry wall didn’t cover the floors. The floors should be one of the last work items done in the midst of renovations. All wet work should already be completed, including drywall patching and sanding and with the home heating system up and running.

It does sound that he was too aggressive in his buffing because from your description it sounds like he has removed some stain. You said it looked good before. Waves are definitely equipment issues while chatter can be a machine issue or perhaps and indication of a loose floor which is rattling under the sanding machine. Blotchy stain generally indicates improper preparation when sanding. For example if the edges are lighter or darker than the main area of the floor.

Follow-up: I see. There was a 5 gallon bucket of sanding dust from this week when they buffed, is that something you typically see when buffing with a 220 grit?

A: I use a vacuum system so you don’t see any dust, but not a chance. It is just suppose to be a quick buff of the surface of the finish. You shouldn’t get anywhere near a bucket of dust from that.

Later Q: I wrote you back in march about a flooring issue. I wanted to ask if there was anything that could be done to prevent a raised grain. Our floor guy is redoing the floors for a second time and we chose to do a Waterloo to enhance the look of the grain. After that he sealed and then applied 3 coats of waterbased matte poly, buffing between each coat I believe. This time around I would like to prevent the grain feeling so raised so it won’t catch on things or trap dirt and debris. He said this occurred from water popping coupled with water based stain, but I can’t help but think surely there is a way to ensure a smooth finish. Any suggestions? Thanks!

A: He can buff the finish after the first coat. Norton Abrasives has created pads, one of which is designed for water borne coatings. It will smooth it out, knock down grain raise, etc.

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