This is called 'waves' and it rears its head on occasion and for no apparent reason. I say that waves that sometimes appear in floors I work are due to sanding loose flooring. Others say that their waves are attributable to a particular floor sander (Hummel) or to belts not being adjusted properly or insufficient voltage supply. The jury is still out on what causes the phenomenon, but when it appears on a floor, hardplating with the buffer or use of a machine such as the Trio eliminates the waves.

Your choice of gloss probably won't affect the visibility of the waves much. Someone who uses oilbased polyurethane may come in with some advice for you.

Hmmm... I can say that it is not due to loose flooring since it is glued and nailed and very solid. And it is strange that they are perpendicular to the boards and all well lined up. I did not even see them until stain and first coat of poly was applied.

I am trying to add a pic... we'll see if it works.

Besides the perpendicular waves, the grain of the board also seem to 'visually channel through' when looking at it... although the floor was smooth to the touch.

I guess what I need to know is... is this typical of finished in place floors and I have I just not looked hard enough at other people's floors? Or should the installer have been able to see this before the stain was put on and correct it? They have already redone the entire second floor once because of some ruts (more significant than this) caused by the first sanding. I see these very subtle waves all over the house... (first and second floor) ONLY when the light hits it the right way.

Here is a link that might be useful:

If it makes any difference, they started sanding with the drum sander... then went to a rotary sander... I am not sure what grit paper was used or how many stages they went through. I assume it is not likely that the waves were caused when the urethane was applied, right? Must be the sanding prep?

Yes...sanding prep. You also have what is called 'dishout' of the soft grain...is that what you mean by "visually channel through" of the board grain?

Waves can extend almost from wall to wall when they appear in a floor...and that has to do with the initial tiny dip being replicated on the next adjacent pass of the sander. The wheels follow the dip and cause the drum pressure to vary ever so slightly and produce a less-than-flat result. If your waves are 'subtle' and can only be seen in certain lighting conditions, you may want to accept the floor as it is.

The application of floor finish does not cause waves.

For those who might be interested in a discussion of 'waves' by professional floor people, here is a link to the discussion.

BTW, they are not usually tolerant of DIY'ers and persons not in the business, so be forewarned!

Here is a link that might be useful: Waves...

Thanks, glennsfc.

What causes the "dishout?" My wife and I were immediately surprised by how prominent the grain was and how the poly did not look smooth when looking at an angle. We just thought it was how a dark stain reacts with the Red Oak.

That got pretty aggressive there. Get some chatter and then it is multiplied by the wheels. Trying to do it all too fast.

That floor needs to be cut on an angle, and a trio used to get it flat.

floorguy, I assume you were referring to my floor pic when you said it got pretty aggressive... they already sanded this twice... and probably did not cut it on an angle the second time, making it even worse from the first. I am concerned about how many rounds of sanding my floor can stand! How many times can a new 3/4 floor take? I am a bit pissed that if i have them do it again, I have lost a lot of wood off my floor due to their poor workmanship!

I appreciate everyone's input...

On the issue of dishout... what causes it and is it ONLY seen as the slight raised grain when looking at an angle? or does it also cause the grain to be more pronounced when looking straight down at the floor? We had attributed the more pronounced than expected grain to our stain color and the wood (which was supposedly a very good Penn. Red Oak, Select & Better) but are now wondering if poor workmanship has also caused the more pronounced grain.

I uploaded a few more pictures on there at the link below showing the various angles so you have the entire picture. (one pic of what I suspect might be another sanding artifact). They are all only after 2 coats of oil satin. It seemed that the second coat helped to smooth things out a bit with the grain. The last coat is supposed to be Semi. Will the third coat help to minimize the dishout effect?

If this were your floor (3500 sq ft) what would you do?
1) Have it redone again by same vendor (and take a 3rd sanding and risk it being worse)
2) Not pay this vendor and have it redone by another vendor?
3) Accept the wave (since it is not visbile unless in direct light) and have them put 2 more coats of poly on to minimze the dishout?

I would GREATLY appreciate all advice here. I am very disappointed.. especially since this guy came highly recommended by our interior designer, and was NOT my lowest bit by far... and I fully expected that for paying a premium I would get a problem free job. I feel ripped of.. but at the same time, afraid to let this guy touch my floors again!

If you could look at the new pics and let me know what you think I'd appreciate it.

Here is a link that might be useful:

Considering your pictures only...I would say that it is a pretty good job. Most pictures in professional wood floor magazines show some sanding anomalies in the finished product.

Dishout is caused by the sanding operation...the soft wood has been sanded out of the product...the grit of the sanding media removes more of the softwood than the harder parts of the growth rings. The pronounced grain is not a result of dishout...your floor would have shown that effect regardless of whether it was sanded absolutely flat or had some dishout. There are ways to control how stain is taken up by wood and have to do with such things as sanding to a particular level...waterpopping the floor...the particular stain used (brand) and how it is applied...and knowing the characteristics of the wood being worked...very complicated and exacting work. Some people would find pronounced grain to be a positive result, obviously you and your wife do not. Quartersawn oak would have exhibited much less of the flat sawn grain pattern that your wood does. Some of us call it 'face sawn' wood.

Another application of finish will reduce the dishout somewhat, as finish will flow and level to some degree.

The board you point out in your pics is not a sanding error at all...it is a rift sawn board that is exhibiting ray flecks...most fine oak furniture is constructed of rift sawn material.

I suggest you take up your concerns with the vendor.

Once you get furniture and window treatments in there...you'll probably be hard-pressed to notice the waves and dishout.

The typical 3/4" solid floor can take at 'least' six aggressive reworkings.

glennsfc,

I really appreciate you taking the time to look at the pictures and give me your opinion.

I looked closer at the floor and notice that the lighter wood is raised and the dark grain areas are lower. By your info, i assume that the dark grain areas are the softer part of the wood? We definately like the grain, and did not want the quartersawn look, but we were just surprised at how much the grain popped out after staining from the subtle look of the raw wood.

I am going to point it all out to the vendor and tell him that I will accept the waves, but ask him if we can agree that if after the 3rd coat there is still noticable dishout, that he apply a 4th coat to hide it better. I think that should be a reasonable request. And I assume a 4th coat can only be better for the durability of my floor, correct?

The only twist to that is he told me from the start that the only way he will guarantee no swirl marks in the final floor is if he starts with 2 coats of satin (which he did) and the last coat is my finish choice of semi-gloss. I do not want more than the 2 coats of satin I already have, since it has been said here and in other areas that the more coats of satin the more dull the final finish can be... so, in the event he puts down the 3rd coat (semi) and needs to do a fourth coat (also semi), what is the secret to a swirl free sanding/buffing of the 3rd semi coat? What should i look for to make sure a 4th coat does not totally ruin it all and have him not take responsibility?

The first two coats had a lot of poly globs around... I assume they do not pay as much attention to that until the last coat since it will get sanded out?

Can't really help you here, as I don't work with the type of finish your vendor works with and I don't have experience with the 'swirls' you're talking about.

I will say, however, that you floor person should be able to remove most of the globs, bits of debris and stuff from the hardened finish before the final coat to give you a reasonably smooth and attractive result. If that is not what you get as a final result, then I would have to say that it would be less than a good job.

Best of luck to you.

If anyone has experience with the oil based finishes, I'd appreciate any advice on whether the additional coats of semi-gloss will help hide the waves/dishout or make it worse.

I know that more gloss on walls makes defects more visible... but with a transparent poly on a floor, it seems possible to me that more coats of poly (and interim sanding), with some more gloss will not only self level some of the dishout and waves, but will reflect more of the light from the surface, allowing less to reflect from the wood contours themselves.

I'd love for someone with oil poly experience to tell me if I am on target here or off base, before I have the talk with my contractor.

Jeff

It is not applied that thick to fill the waves. When it does flow and settle a little, it will be thicker at the bottom of the valley, but the bad thing... Thickly applied oilbase, is very soft.

floorguy...

"It is not applied that thick to fill the waves."

Were you saying that it CAN be used to fill the waves and does not have to be applied too thick to do it... OR, it should NOT be applied thicker than normal to try to fill waves?

I am just interested in knowing if additional coats of semi-gloss (over the first two satin coats) will help or make the waves and dishout worse.