Brand new polyurethane coat peeling


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Old 07-14-15, 07:23 PM
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Brand new polyurethane coat peeling

Hello, I'm hoping to get some advice on what to do about my floors.

Last week we went through the whole process of emptying the space, renting a sander, sanding down the floors and giving them three coats of polyurethane. This week, though, we've been finding spots of the polyurethane that are peeling up.

Here are some more details about what is happening:

We sanded down till the wood was bare, although there were some stains that we could not remove.

We began with 24 grit paper and worked our way up into the 100s.

We hand-sanded spots the machine couldn't reach.

When we finished sanding, we vacuumed the floor three times and wiped it down with cloths to make sure we got as much dust off as possible.

We were running an A/C to make sure it was not too humid in the house. We were pretty comfortable the whole time - no sweating.

We then brushed on a coat of Ben Moore Stays Clear polyurethane (Low Lustre) and let it dry for 2.5 hours.

We then rolled on a second coat and let it dry another 2 hours before putting on a third coat. (We followed the instructions on the can, though I see the instructions on Ben Moore's website are a bit different, especially when it comes to furniture, heavy traffic etc.)

The can said nothing about furniture, but we had little choice but to move furniture back on that evening.

I have felt pads on the bottom of most of the furniture (I thought it would help protect the new floor...)

The other day when we moved a living room chair, one of the pads had slipped off and the adhesive gunk on the bottom pulled up a chunk of the polyurethane. Also, I noticed a similar peeling near a heavily used dining room chair.

When I examine these spots, this is what I notice:

The poly came up right down to the bare wood. The edges of the patch can be peeled up, and it seems like I could just keep peeling if I wanted to. In other words, it is not just where it was damaged that it can be pulled right off.

I've been trying to find information online, but I can't really seem to figure out what to do about it, or what we did wrong.

I am gathering that even though it is dry, it still needs to 'cure' and that this can take quite some time. But I don't know if this peel-ibility is normal for this stage, or if it means we did something wrong. Redoing it, unfortunately, is definitely not financially feasible right now...

Any advice would be greatly appreciated.

Thank you!
 
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Old 07-14-15, 07:42 PM
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Poly should always be scuff sanded between coats, which removes impurities in the finish and promotes good adhesion. I can't believe it would be ready to recoat in only 2 hrs. Website says 3 hrs to recoat, 24 hrs for traffic. Sometimes rolling will not promote the best adhesion. When poly is applied too thick, adhesion can be affected... thin coats are better. Website recommends a 4 mil film wet. If you put it on too thick, it would be a bit rubbery to the touch and might come off when scratched. So my guess is that you rolled it on too thick.

Putting furniture on it too soon is also taking a huge risk, as you have found out. No professional floor company would dream of coating a floor with 3 coats in one day and then putting furniture back on it to boot.

Don't really know what to tell you other than to scuff sand and touch up the affected areas.
 
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Old 07-15-15, 04:20 AM
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I agree with everything X said. I don't often use waterbased poly and don't think I've ever used that particular poly but no way should you apply 3 coats in 1 day! Just because a coating is dry to the touch doesn't mean it is dry throughout and is ready to be recoated. Applying more poly on top just slows down the curing process. Setting heavy objects [or traffic] over uncured poly affects the softer not yet dry poly underneath.

Floors don't touch up well If you can sand individual boards and recoat just those boards it will look better than just sanding and applying poly.
 
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Old 07-15-15, 06:27 AM
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Just for the details - polyurethane cures rather than drying. That means one coat is independent of the other coats. Scuff sanding creates nooks and crannies for the next coat to flow into while wet so that you get a mechanical bond between the coats. Skip the sanding and the layers will peel.
 
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Old 07-15-15, 06:45 AM
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One other thing, I know the can probably didn't suggest it, but I probably would have used a sanding sealer for the first coat.
 
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Old 07-16-15, 07:43 AM
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Thank you for your replies!

I have a hallway still to do, and now I have a much better idea of what to expect in terms of drying times, sanding etc.

The hall is already sanded down. I just need to stain it and polyurethane it. The guy at the local Ben Moore paint store (where all the local contractors seem to go for advice) told me that I could use an oil based stain under my Stays Clear waterbased polyurethane. I asked him again, just to make sure, and he seemed to say it was no problem.

From art school I recall being told that you always put 'fat on lean' - which is to say, you can paint oil over acrylic, but not visa versa. They said the oil breathes, which will crack the acrylic, which doesn't.

So his advice sounded really strange to me coming from that perspective (on the other hand, we used to spray Crystal Clear over each layer of oil without any trouble).

Do any of you know if it is ok to use an oil-based stain under water-based polyurethane? If so, how should I go about it? I see that I should sand between coats of poly, and make sure they have more dry time. But should I also sand after the stain? I'm a little afraid to just read the cans now...

Thank you again for all the information!
 
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Old 07-16-15, 08:18 AM
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Wait for Mark's opinion on this but I would not do it. That said, I use oil based poly because I like the color it adds.
 
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Old 07-16-15, 09:07 AM
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You can use an oil base stain under water based poly BUT you need to give it extra drying time. You can fudge a little when recoating over oil stain with oil poly/varnish but not when the poly's water based.

Stain isn't the same as an enamel paint. When switching from an oil enamel to latex you must first apply a solvent based primer but on the exterior things change and you can successfully apply latex paint over weathered oil base paint.


While you need to sand [and remove dust] between coats of poly there is no need to sand the stain coat. Sanding the stain would likely cause you to sand thru the stain in spots

edit; when top coating oil base stain with water based poly it is extra important that all excess stain be removed, too heavy of an oil residue can affect the poly!
 

Last edited by marksr; 07-16-15 at 09:23 AM.
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Old 07-16-15, 09:42 AM
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Yeah, I wondered about what kind of stain you used and forgot to ask. If you used on oil based stain and didn't give it enough time to dry before putting on the poly (minimum 24 hrs... or more depending on the brand) then that is surely part of the problem!

A lot of DIY'ers get into trouble because they rush things and don't allow enough dry time because they just want to get it done and don't know any better.

So how long did you wait after staining before you applied the water based poly?
 
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Old 07-23-15, 01:23 PM
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The floor that was peeling actually had no stain. It is oak, and we liked the look of it unstained and we were told that a stain would only accentuate the imperfections and soak into the parts where the wood was already discolored.

Fortunately I haven't been finding any more peeling, and the floor feels a lot harder - less tacky when you run your hands over it. I'm hoping that is the end of it...

The upstairs section I have yet to do is spruce (so I am told), so we are planning to use an oil stain. I'm planning on giving it at least 4 days before I put the first coat of poly on it.

Thank you all again for your advice.
 
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Old 07-23-15, 01:26 PM
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No stain is fine but all flooring should be finished with poly or other as bare wood will absorb spills and the stains left behind often cannot be removed.
 
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Old 07-23-15, 02:13 PM
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As long as the excess stain is removed, the stain should be ready for poly after 24 hrs although humidity and cool temps can slow down the drying process. IMO it is never a good idea to apply multiple coats of stain! the first coat of stain somewhat seals the wood making it difficult for more stain to be absorb and stain isn't formulated to lay on top of the wood - it needs to penetrate with any excess removed.
 
 

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