Hardwood floors: What could leave spots of bare wood?

October 9, 2016 5:25 AM

We are finding bare spots on our hardwood floor, (i.e. apparently missing the polyurethane sealant). We have found spots in the middle of the floor (away from windows) in a few locations (images here). The wood looks bare. The edges of the spots missing the polyurethane are crisp. I do not believe this is water damage. It doesn't appear to have "bubbled up" characteristic of the water damage that I've seen.

We had new hardwood floors installed one year ago. Some installation details:
-Professionally installed by a highly-rated installer
-American red oak acclimated for 7 days before install
-At least 2 coats of polyurethane (Bona Sport 350 I believe)
-The floors looked great after installation
-The spots are definitely new, not just newly discovered.

I contacted the installer. They haven't heard/seen this, but offered some suggestions for how to repair/cover these spots.

These bare spots are well-defined, not streaks. To us this implies droplets of something as opposed to streaks from some foreign substance on socks/paws/feet. The spots are in high-traffic areas (corridor between living room and kitchen) and low-traffic areas (near window, in front of dresser).

Crackpot theory: We got a dog in March. Could droplets of pet urine or corrosive dog drool cause this kind of damage? Maybe the bittering spray we use to dissuade destructive chewing?

What household products can dissolve polyurethane in a highly localized manner?

Is it possible the wood was locally contaminated during installation, and the polyurethane just took some time to slough off?

posted by KevCed to Home & Garden (13 answers total)

I don't think it's dog drool. My golden drools all over my darker hardwood floors and while the spots must be scrubbed with a nylon scrubby pad to get them up, it doesn't harm the finish at all. Good luck figuring it out! It must be distressing. Also, you may want to add what you're cleaning them with.
posted by cecic at 6:17 AM on October 9, 2016

Those definitely are spots from a solvent. Perhaps rubbing alcohol, nail polish remover or perfume?
Pet repellents are usually quite friendly to furniture and household items because of the nature of the product.

Oil-based finishes offer better durability against damage such as this but no finish is perfect.

Assuming the spots weren't bleached in the process they should repair quite easily.

If you have corrosive dog droll you may have a bigger problem on your hands :)
posted by ashtray elvis at 6:30 AM on October 9, 2016 [3 favorites]

Is it possible that something masked those spots on the floor, back when the polyurethane was applies?
posted by amtho at 6:30 AM on October 9, 2016 [2 favorites]

I'm just throwing a dart here, but if this is happening all over, in high and low traffic areas, I think it may have been a faulty batch of finish or some kind of installation problem. One year is way too early for this kind of wear.

You won't be able to fix this without a visable overlap in the finish.
I would personally probably push the installer to refinish them completely.
If your installer isn't cooperative, get a second opinion.
posted by littlewater at 7:25 AM on October 9, 2016 [1 favorite]

That's not wear. It looks very much like some liquid fell on the floor that is dissolving the finish. It might be any number of things, but not dog drool, urine, or bittering spray. Perhaps you could do an inventory of the solvents you have in the house and think if any of them could have dripped on the floor?
posted by ssg at 7:31 AM on October 9, 2016 [1 favorite]

Nail polish remover? Dogs won't do that, they'll scratch your finish but they wont dissolve it.

Was it raw wood or reclaimed btw? Poly won't stick to wood that's been waxed or has wax or various other substances on it. I wonder if it had something on the wood, although if it's in high traffic areas I think the drip theory is more likely.
posted by fshgrl at 10:33 AM on October 9, 2016

Do you have kids? I can totally imagining my brother and/or myself doing some kind of experiment with/to/on/above/across the new floor, and then making a vow to never tell our parents about it.
posted by amtho at 10:56 AM on October 9, 2016 [1 favorite]

Response by poster: @fshgrl: New wood, not reclaimed. Some in high traffic, and some in low-traffic.

@ssg: I did an inventory, but came up short. I was hoping someone would say "homebrew sanitizer is murder on hardwood, do you homebrew?"

@amtho: No kids. However, as a former clandestine chemist, I like that theory.

I may do an experiment on the floors in one of our closets to get positive confirmation. My doubt about accidental household solvents is that the spots don't correspond to places you'd use them, and they look like drops not tracked streaks...

I'm also worried that whatever nasty solvent that is damaging the floors may be harmful to the 2 and 4-legged residents of the house.

I guess I'll follow up with the installer. I'm hopeful that we can refinish locally and blend the finish, rather than refinishing everywhere...
posted by KevCed at 1:09 PM on October 9, 2016

Modern polyurethanes are almost indestructible, the fault is most likely in the application. Did the contractor wear gloves? Skin oils are enough sometimes. Was it hot, like dripping sweat hot? Moisture can mess things up as well.

This is indeed a real pain to fix properly (sorry) but it can be done without refinishing the whole floor. Good luck.
posted by Admiral Viceroy at 1:21 PM on October 9, 2016

@ssg: I did an inventory, but came up short. I was hoping someone would say "homebrew sanitizer is murder on hardwood, do you homebrew?"

Star San is an acid that will remove many types of finishes. If this, or something similar, may have dripped on your floor I expect that it would remove the finish.
posted by The Architect at 4:23 PM on October 9, 2016

Perfume/cologne? I mean, it would be unusual to have drops of perfume in multiple places in the house but I have childhood memories of a finished wood dresser spoiled by spilled perfume.
posted by mskyle at 7:15 AM on October 10, 2016

Response by poster: @Admiral Viceroy: We had them done this time last year. If memory serves, it was seasonable fall weather. I don't think it was sweaty/grimey. The installer was meticulous, and I think he would own up to a workmanship issue like this.

@The Architect: I have and use Star San, but the location and configuration of the spots, and when we started finding them don't line up with that theory. I'll definitely test it on a hidden spot, which is also where I plan to practice my spot-refinishing technique.

I'll ask our cleaning lady if she is bringing anything from outside. She uses our products, and none of the ones we have are harsh enough, but maybe she's got a secret weapon that is de-polymerizing my floor finish.
posted by KevCed at 11:54 AM on October 10, 2016

My star San on light wood accident resulted in darker, reddish staining if that is a helpful datapoint. Didn't look like your damage.
posted by slateyness at 7:07 PM on October 10, 2016