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How long does polyurethane take to FULLY cure?

Ross Michael
8 years ago

Wondering how long it takes for polyurethane to completely cure on old flooring? Reason I ask is because we had our floors refinished about a month ago (home built in 1800, floors just about as old), and after working on a stepstool for an hour or so installing a light, I noticed it scraped off some of the polyurethane. Is this normal? Am I just terribly stupid and should have been smart enough to put something down to protect it, or was it refinished poorly? Any help would be greatly appreciated!

Comments (14)

  • gregmills_gw
    8 years ago

    Was the floor sanded down to bare wood? or just another coat of finish applied?

    If everything on the sanders end was done correctly, and the enviornmental conditions were within range, Oil Based Polyurethane fully cures within about 30 days.

    You have issues, but need more information before anyone can determine where things went wrong.

    Should you have used something to protect the flooring? Yes, is the damage caused by the step stool because there wasnt anything protecting the floor? right now it doesnt look that way.

  • Ross Michael
    Original Author
    8 years ago

    Thanks so much for the quick and informative reply. Sad to say I can't give a definite answer in terms of the sanding. I know it was sanded down several times to bare wood when we were experiencing inconsistencies with the stain on the old wood, however I can't guarantee it was done for every coat of poly (contractor said it was, but I wasn't there some days, especially at the end). The marks are certainly from the legs of the stool, however it just seems like something else must be going on for a stool to make those kinds of marks. Thanks again!

  • gregmills_gw
    8 years ago

    Alright, full disclosure on my end, i am not a certified flooring inspector, so anything i suggest is purely speculation based on experience. But it looks like there was adhesion issues with one or more coats,

    The way the finish kind of flaked off is a red flag to me. Did they add stain to any of the coats of finish? a normal acting finish wouldnt flake off like what you are seeing.

    As of now based on the information you have given i would say something went wrong during finishing coats.

  • Ross Michael
    Original Author
    8 years ago

    Thanks. It's a 200+ year old home we're in the middle of a remodel with that's built into the mortgage, so it makes it even more fun trying to do this with the bank's deadlines and timelines for paying the right people. In your opinion, is this something that would require the job to be redone completely, or can it be taken care of by just sanding the finish off and reapplying?

  • gregmills_gw
    8 years ago

    if the issue truely is adhesion related, it would need to be sanded again and started over from square one.

    There are a lot of other good pros on this site, that will speak up and give their opinion, but i think you should look for a certified hardwood flooring professional in your area to come take a closer look.

    Ross Michael thanked gregmills_gw
  • User
    8 years ago

    Is this a water based finish or oil-modified polyurethane?

  • Ross Michael
    Original Author
    8 years ago

    Sorry for the delay. The poly is oil-based. I've included a picture in case specifics help.

  • Ross Michael
    Original Author
    8 years ago

    Thanks for the great input. I'm almost positive this was the last coat put on there, especially since there are about 8 empty gallons of poly left behind, all of the same type.

    Here are the bottoms of the step stool. It's a larger, three-step one that is a bit heavy. The feet are a hard plastic. Let me know what you think!

    Thanks again!

  • User
    8 years ago

    Sounds logical. Those feet don't look too bad, especially if they sit level on the floor to distribute the weight.

  • Ross Michael
    Original Author
    8 years ago

    The contractor is coming by tomorrow to take a look. I'm gonna try that test you mentioned with the measuring tape to see how big the problem is. Thanks again!

  • User
    8 years ago

    Anything that's hard and slightly rounded will work. On finishes that are very poorly bonded you can even use your thumbnail.

  • AnnKH
    8 years ago

    Good luck - I would be very disappointed if my newly refinished floor looked like that.

  • glennsfc
    8 years ago

    It might also be a problem associated with the finishing product itself. In other words, defective finish. I don't work with oil based products, so I can't tell you that I've seen this happen with floors I've worked. But as jfcwood said, the peeling looks like what we see with waterborne urethanes. Good responses from the other pros.