Would need to see photos of the swirls to help determine cause. It is one of the two causes:

Improper sanding prior to staining or wrong grit was used when buffing inbetween coats.

Thank you so much for your response. Had trouble uploading photos with initial post. Uploaded 2 finally. If you zoom in, you can see all the swirl marks.

Those marks are from the sand and prep prior to staining. You will need to rework the project if, it is visible from a standing position. The final grit needs to be finer. Industry standards is 120 grit for a final cut. Floor boards should be mark free before applying stain. Applying another coat of poly will not hide it.

You cannot fix bad sanding with a rough grit by slopping on more goop. The sanding has to run through the progresdion properly.

Should I ask the flooring guy to start all that again? This is a nightmare. It's at least 2000 Sq feet of hardwood floor. Staircase doesn't look bad as they used a different tool for that.

If, it looks bad, then they need to fix it. Unless , you are willing to accept it. Budget companies do not allocate enough tine to do the job right. If, they are not willing to make it right. Then you know they are over budget.

The buffing after 2nd coat was very deep also as most planks are left with minimal stain only. I understand that each wood Plank will take the stain differently and there could be multiple shades on the floor but dark cocoa stain should not appear like raw red oak with a coat of poly. After stressing over our dilemma for days and after giving floor some time, we realize that we may have accepted those swirl marks if the stain remained dark enough but most planks are left with minimal stain and that's why those swirls show a lot more as bare red oak shows through poly. What would be the easiest solution to this problem? Any input would be appreciated.

The easiest solution is to apply a coat of tinted poly to cover it up. This would mean going darker. The installer still has the risk of messing it up with lap marks, if, they are not experienced with the product.

Are flooring guy finally came back and after we showed him all swirly marks and long discussion, he is willing to sand again and do it all over again. Question for you. How deep of a sanding would be needed to get to final buffing and staining. Would that damage the hardwood? Make it too thin? He kept saying all refinished hardwood floors have swirly lines from sanding and they are inevitable. I asked him what grit he used to do the final buffing before staining and he said we always use 120 and 150. In the end he said he will do the whole floor again minus the staircases as they look ok. What kind of sanding will be needed this time? Would one light sanding be sufficient to reapply stain?

Floor guy will need to take it to bare wood. There is no short cut to quality.

What he says is true. There will always be some level of swirls. It just needs to be not visible from a standing position 2 feet away.

If, they are taking it all the way to 150 grit. It should be flawless. 120 grit, there will be minor swirls. 100 grit or less, swirls are significantly visible. They need to be more thorough with the sanding. inspect the sanding with lights.

Thank you so much for your insight and advise. The work resumes today. They are starting the sanding. We used bona drifast stain using 2 parts mahogany and 1 part cocoa. Some planks did not absorb any stain and I can see pale red oak color. What is the cause of that? He used a machine to apply the stain(don't know what it's called). I understand there can be variation in stain on different planks but in every room, there are several isolated planks that look like original red oak color. He says stain should not be applied twice or it peels. On Bona drifast website it says use 2 coats of stain for darker shades. So what could be the root cause of some planks not getting any stain? Sanding was not uniform or its a common occurrence and 2nd coat of stain would help? Also, do you advise 3 coats of Bona traffic HD? With buffing before the final coat? I have PTSD from what happened with our floors but at least flooring guys came back and trying to fix the problem. I will stay positive and also taking this as a learning experience so I can share with other friends who are planning to get refinishing done.

Post photos

I have uploaded some pics. Unfortunately it's cloudy today so light is not great. But you can probably see the issue in some pics. Staircase is not bad and the stain I chose is what you see on the rail but I understand it's a different wood. I personally feel that there is issue with staining too, not sure what the cause is but you might be able to tell. Again thanks for all your input. I saw pics of floors done by you and they look amazing.

Polyurethane they used is Bona Traffic HD. 2 coats on first day, waited 4-5 days before the 3rd coat after buffing

You will get boards that appear to take no stain at all, that is wood unfortunately.

What you have is normal. if , you want it more dense. you would need to apply aniline dye first. but, youre past that point.

They are sanding today. Staining will start at some point tomorrow or day after tomorrow. The pics I sent are from the first job. They are sanding it to bare wood today. He himself couldn't deny the swirls especially on the very light stained planks. What is this aniline dye?

Just another colorant that penetrates deeper into the wood pores. 10 or 15 years ago when the super dark wood trends was in. All those furniture pieces have aniline dye based stains.

Or water pop it. But, you need higher end skills for either dye or water popping. The jury is still out on whether those exist with this flooring person. It's in their favor that they agreed to do over. But if they can't get the sanding right from that, do NOT let them proceed to the stain stage.

Color popping was done last time also. He used a buffer to apply stain and the color came out much lighter than the sample we tried on a 2 x3 ft area. He is thinking if he does apply stain again with the buffer, the stain may come out lighter. He is thinking using a rag and doing it by hand and he believes we will get a darker stain, closer to what we chose. Is that true? Also, for final buffing He will use 150 grit. Are we doing it right this time? They have been sanding since yesterday and will make floor ready for staining tomorrow.

If, the stain is too light with 150 grit. Stop at 120 grit. The lower grit will help with stain penetration. Just has to make sure it's mark free.

I'm even more confused now. I thought we need final grit to be 150 to avoid swirl marks?

Watched YouTube videos and tried to understand.Seems like technique is more important. He is going to be using 100 120 150. Hopefully they will do a good screening this time.Are there any problems with applying stain with a rag

You will get the same result with both methods. It’s less work with a buffer.

Are abrasions a must in between 3 coats of Bona Traffic HD?? And what should be the order and what kind of buffer should be used for that?? Bona website says no abrasion needed if 3rd Coat is done within 48 hours of first 2, is it true?

Your swirl issue is from buffing before the staining, not between urethane coats. There's a fine line between buffing too little and ending up with a good color and swirl scratches, and buffing too much which gets rid of swirls but ends up too light. Floor sanding is essentially scratching the wood with smaller and smaller scratches. When staining, you'll almost always have some scratches if you look close enough. That's why G&S mentioned inspecting from a standing position. Inspection is also done under normal lighting conditions. In general a 100 grit screen should be smooth enough for the last sanding (though I generally fold it and rub it together and avoid starting where it might show swirls), and I wouldn't recommend going finer than 120. Water popping after 120 will help achieve a darker color. Some guys swear by applying stain with a buffer and pad but I've seen more swirls result from that technique. I prefer applying with a trim pad or lambswool and wiping by hand.

Right before the final screening, the floor should be vacuumed, and anyone entering should avoid tracking in any grit that could end up under the screen on the buffer. Also pay attention to whether opening and closing doors could pull in grit from outside or from under any trim.

"On Bona drifast website it says use 2 coats of stain for darker shades."

That's odd, because I don't see that information here on the Drifast TDS: https://www.bona.com/globalassets/catalogassets/bona-drifast-stain-tds-7-2021.pdf

Please cite your source for that claim. Applying a second coat of stain is generally advised against.

"So what could be the root cause of some planks not getting any stain? Sanding was not uniform or its a common occurrence and 2nd coat of stain would help?"

Nothing in any of your pictures backs up your claim and frankly it defies logic. A lighter board between two adjacent darker boards has to have been sanded the same. The difference is in the density or grain structure of the board.

"Also, do you advise 3 coats of Bona traffic HD?"

If your floor is water popped it should get 3 coats of finish. Bona recommends two coats, unless you have high traffic areas (as in a retail environment). You can read that here, which also gives guidelines on sanding grits and intercoat abrasion: https://www.bona.com/globalassets/catalogassets/bona-traffic-hd-tds.pdf

"I have PTSD from what happened with our floors"

I'm not going to say what I really think, but you should rethink your definition of trauma.

They abraded before the 3rd poly coat last time but they did that abrasion and 3rd Coat after 4 days. They called it buffing before the last coat. It was pretty messy and not sure if abrasion of poly coat is also called buffing. This time plan is to do 3rd coat within 24 hours and abrasion before 3rd coat. Let' s see how that goes. Thanks for all your input G & S Floor Service!