We are just had our oak hardwood floors refinished. We are disappointed that the finish is much rougher than the smooth finish on a room in the house that was refinished four years ago. We showed the contractor this room before he started and he assured us his finished floors would be just as smooth. When they had finished sanding and had applied the stain, I felt the floor and it felt rough. I looked at the drum sander and saw they had finished with 60 grit sandpaper. I have read the final sanding should be 80 to 120 grit. I asked the contractor about this he said he would screen with 120 grit sandpaper in between the three coats of polyurethane and this would make it "as slick as an eel". He then proceeded to apply the polyurethane. Three hours later he said he was finished. I expressed my surprise that he could apply three coats so quickly. He said the polyurethane dries in 30 minutes so it was no problem. The floor was wet and I couldn't touch it to feel the finish. I paid him and he was on his way. Now that it has dried we have discovered that the finish is still rough. He left two empty one gallon cans of polyurethane behind(in the trash). It's IDI Wood Pride water based Clear Gloss Varnish 1808-0000 and Clear Satin Varnish 1802-0000. I don't know why he would use both gloss and satin when we had asked for satin. I read on the can label that the final sanding should be 150 grit or finer. It said the drying time for recoating is three to four hours. It seems the contractor has rushed the job. I called him and explained that the floor was much rougher than what we expected. He said it just needs another coat of polyurethane and he would do that. I have my doubts that this will give us the finish we want. Will an additional coat or coats of polyurethane smooth out the finish? Or, should it be resanded with a finer grit of sandpaper? Any advice would be much appreciated.

Your "contractor" did a "blow and go" job. You're correct on your assumptions. 60 grit is too rough to finish sand a floor and one cannot apply (3) coats of finish in three hours, unless it was lacquer. Sounds as if you have every right to call him back to remedy the problem. Wood floors do not have to be flawless, but they should be smooth, not rough. Maybe he'll be able to apply enough finish to make it smooth enough, maybe not. If not, a re-sand would be in order.
Out of curiosity, do you take the lowest bid?

Thanks for your reply. So it might be possible to remedy the problem with more polyurethane? This was not the lowest bid. It was $200 higher than the quote I received four years ago from the contractor who did the one room, so it seemed to be in line. The contractor kept talking about how he had thirty years experience and he fooled us into thinking he was a real professional. We found him from an ad in the newspaper. I would have gone with the previous contractor but unfortunately he passed away last year.

I spoke with the contractor this afternoon. Here’s what he said:
He admits the final sanding was with 60 grit sandpaper but he says he then screened the floor with an 80 grit screen after the final sanding and this is equivalent to a final sanding with 80 grit sandpaper. He says anyone who says you need a finer grit sandpaper for the final sanding does not know what they are talking about. When I told him about this forum and my research and even the label on the empty can of polyurethane that dispute this, he stood by his statement and said all of these sources simply do not know what they are talking about. He says sanding with a finer sand paper closes the pores in the wood so they can’t absorb the stain and polyurethane. He says his method of finishing with 60 grit and screening with 80 grit will produce a much more durable floor. He also said the floor will have a smoother finish when it has had a chance to fully cure. He went on to say that while a finer sandpaper will result in a smoother finish, that finish will quickly wear off. I asked why the floor that was done four years ago was holding up so well. He said they might have used oil based polyurethane and that water based polyurethane is not as smooth. At one point in our conversation he claimed he did the final sanding with 60 grit because it was necessary to get out the pet stains(most of which he did not get out). He says he will screen one more time and put on another coat of polyurethane and this should satisfy us. Any comments?

If he screened with 80 and then stained, You would most definitely see the swirls and scratches left from 80 grit, after the stain was applied. YIKES!!!!

Since your not complaining about swirl and scratches, he did not use 80 grit on a buffer. I say BS.

If he sanded to 60, there are some high peaks in the cut. The finish flows into the valleys, leaving the peaks up(your seeing it right now) This causes accelerated wear through, as very little finish is on the top of the peaks.

There is no way he coated with the amount of coats he says, in the time you saw him there.


You got HACKED!

His procedure is not recommended by or done by any of the many pros I know and converse with around the globe. The lowest grit used on the drum sander would be 80, with 100 being the preferred grit. That is UNLESS one is using a rotary sander like a TRIO. But that machine is not a buffer but a true orbital sander. A buffer is not an orbital. Then with a trio, one would normally finish with 100. The only reason a water based finish would be "rougher" is because the finisher did not take the necessary steps to provide for a smooth finish. The guy probably knows how to do it correctly. He just didn't do it, in order to get it done fast and cheap. He cut corners and got caught. I cannot say if what he does will improve it because I cannot see your floor from here. Don't expect a table top finish but it shouldn't feel like sandpaper either.

Thanks again for the replies. Is there anything to his argument that a final sanding of a grit finer than 60 will close the pores so the stain and polyurethan won't penetrate into the wood? What about his claim that his method results in a more durable finish?

In short, no.

Nay nay. Pores are pores and are not affected by sanding, other than perhaps filling up with fine dust which is vacuumed out befor staining.
I would be surprised if your finish lasts very long. You need a flat smooth surface for maximum durability. As was described to you, you now have microscopic mountain ranges on the surface of the floor, and the peaks are going to erode with time and use, exposing unprotected wood to the elements.
Gee, what similarities between wood flooring and Geology.

Nope, anything finer then 100 and you start to close the pores making the stain not penetrate as well. 60 is usually use for the first cut in some cases.
60-80-100 grit sequence.
40-60-80

The book says 3 sequences. some do it in two if the floor is not in real bad shape.

Dennis you are wrong about pores are pores....You go too fine on that sandpaper and you close the pores up so tight that the stain won't take (ends up being way too light) Put the finish on too soon and you'll have another problem (no adhesion)I've stained floors after a 60 grit cut and I see no problem( what's this peak BS?) you get enough coats on that floor and it will hold up just fine...As for the 3 coats of finish in 3 hours,this guy is a hack (if his first coat has crap in it then he's gonna have it through to the last coat.Try screening between coats,they come out smoother(but can't be done in 3 hours) As far gloss and satin finish (I use gloss as my underneath coats and top off with satin).

The only way you would have the so called mountains you're talking about is if you don't get the 40 grit line out. (I doubt 60 grit sandpaper would leave the kind of mountains you're talking about)I've gone back to look at one of my jobs after 4 years and let me tell you not only were there no mountains, but it looked like furniture

Ask the contractor to come back and apply 2 more coats.

When he comes in, he will buff the floor, vaccuum and coat. He will wait for it to dry, buff, vacuum and coat. This will make the floor more smooth. If you see no problems with the sanding then this will remedy your solution just fine. Its the consecutive layering/ buffing of the finish coats that will make the floor more smooth. He did NOT do 3 coats in 3 hours unless you have about a 100 sq ft.

Well I've been wrong before, but not about wood technology, at least not that has been proven to me.
Peak BS? Nope, go back to floor sanding 101 if you need an elementary level education about the physics of floor sanding.
I suppose if you flood the place with urethane you will fill in the valleys between the scratch lines that 60 grit will leave.

At any rate I am not going to entertain an on-going discussion with you about right or wrong processes. What works for you is fine, for you.
In concluding my side of this "argument" so to speak, I have successfully sanded all the way up to 120 grit paper for many years, followed by hardplating up to 150 on occasion. Never had a problem achieving the desired colour because of a too smooth surface.

Space here for for your closing remarks ( )

"Quality Floor Co" now appears to have appointed himself as grandmaster of all wood floor related subjects. He has seen fit to dig up old posts, then proceeds to tell us professionals with decades of experience, how we're doing things "wrong". This type of attitude does not set well with me. It shows disrespect for myself and others and their experience and knowledge. I will not tolerate it much further. If "Quality" cannot temper his remarks and continues to disrespect the alumni of this forum, he will be gone. Period.