Help and honest advice from the experts on this forum would be greatly appreciated!

My oak floors were refinished with 2 or 3 coats of oil-based 6 years ago. Those floors were recently damaged in the entryway. The damage was caused by blue tape applied by a bathroom remodel contractor to hold down ram board, and the blue tape was left on the floor for over two weeks. When it was removed, it removed the finish in spots in a line where the tape was placed. The local floor companies recommend sanding the damage, or the entire entryway, and applying oil-based polyurethane to the damage, or to the entire entryway. Followed by rescreen (buff and coat) of the entire floor so the entryway will blend in with the connecting hallway, living and dining rooms. (The rest of the floor, which was not damaged, is in very good condition and would not need a coat, were it not for the need to match the damaged area to the rest of the connecting floors.)

My question concerns that last step -- the rescreen of all connecting floors.

One company told me that high quality water-based poly will adhere better to the existing oil-based floor when rescreening. The other 4 or 5 companies who provided estimates all told me to stick with oil-based polyurethane as that is what is already on the floor.

MY QUESTION -- Is the assertion correct that high grade water-based will better adhere to the floors in a rescreen than will oil-based — on an existing oil-based finish? Will water-based, if applied on top of an existing oil-based finish, last longer? Will a rescreen or buff-and-coat of water-based, on top of the existing oil-based, have less chance of flaking off in future years? Finally, some web sites argue that the top-of-the line water-based finishes are more durable. Is that true?

Also, the company who made that assertion proposes to sand the damage, and first apply oil-based to the damaged area to restore the color for a better match to the surrounding floors. They would wait several days and then rescreen the entire floor, and not just the entryway, with water-based. But is 48 hours enough time to wait for the oil-based repair to dry? Some web sites say that I should wait 6 months after the application of oil-based before applying water-based. If that is the case, then I am stuck, and will have to use oil-based for the final rescreening coat as well.

P.S. Aside from the above, every contractor has a different solution, with prices ranging from $800 to over $3,000. The cheapest would only repair and rescreen the entry way, and say the resulting work would match well enough so that only I would notice it. Or just rescreen over the damage in one day. Or, moving up the cost ladder, sand the entry way, and apply two or three coats of oil-based in the entry way over two or three days, and then a final rescreen coat (#4 coat for the entryway). Or sand off everything and start over. No wonder consumers get confused by the options.

I talked to Bona tech support, to find out about this for another post. Their answer: It's a longer period for water over oil. It's the curing time--Bona oil finish takes 14 days to cure, so that's the wait period before you can put water over it. Water-based finish takes 7 days to cure, so you can put oil over water after seven days.

So, you don’t need six months, but it is recommended to wait 14 days.




My opinion is that water-based will generally adhere better on a recoat than oil does. The water-base forms a chemical bond, whereas the oil-base needs to have a mechanical bond. Here, though, it’s your own floor, and you know the history. As long as you haven’t waxed it, or used Murphy’s Oil Soap on it, you should have no problems with recoating using either oil or water.



This debate goes on endlessly. I’d say that two-part water finishes are more durable than oil polyurethane. They’re more modern technology, and they form a chemical bond with the existing finishes.




Given that it’s a small entryway, I’d opt for this procedure.
Per Bona’s advice, I’d have the final re-screening put off for the fourteen days, though, if you use the water-base as the last coat.

MANY THANKS for the excellent response!

One question -- I also posed these questions to a flooring company in Georgia (not where I live) and they were kind enough to respond. That company exclusively uses water-based from what I can tell. The owner said this: "I do not screen floors at all. There is a short video on my website about Clean & Recoat that shows you how I do a recoat and why. In my opinion, as well as most coatings manufacturers, screening dramatically increases the potential for adhesion failure." FYI, that video can be found here:

http://rosebudfloors.com/hardwood-floor-videos/

I was even more confused, if not alarmed, when I read that, because 5 flooring companies who use oil-based poly would rescreen. But I think I understand why, based on your response.

Alloy7, you explained that water forms a chemical bond, whereas oil needs a mechanical bond. That implies that Clean & Recoat (or buff and finish) is the correct approach for water-based. But a rescreen using 220 sand paper or equivalent may, in fact, be the correct approach for an existing oil-based floor, so that a mechanical bond is created.

Have I got that right?

Again, many thanks for the thoughtful, detailed and well informed response!

The oil based poly-urethane re-coating directions from the finish company that I use recommends a 100 grit screen for the mechanical bond.
The coating that is applied after the finish has completely cured will not allow a fresh coat of poly-urethane to etch into the surface so a substantial roughing of the old coating is necessary.
The scratches from the 100 grit screening will not always be completely filled in with just one coat of finish.
I always recommend two coats of fresh finish for re-coating with oil based finish so the second coat can etch into the first coat that starts to cover the 100 grit scratches without such a coarse screening between the coats
and produce an even gloss over the whole floor.

Yes, that's my understanding. I did not see the video, but I'm curious about the assertion that screening increases the potential for adhesion failure.

Anyway--not that you'll be doing the screening yourself, but the recommendation for the finishes I use is to use 180 grit for oil, and to use 220-240 for water.