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Help! Lap marks in poly on new floors!

Posted by ruddycat (My Page) on
Wed, Jan 8, 14 at 13:05

Hi! We recently had 1500sf of 4" white oak installed on our 1st floor. It was stained with Duraseal Antique Brown & finished with 3 coats of Minwax satin oil-based poly. To make a long story short, after multiple attempts to get the 3rd coat of poly applied without lap marks, our flooring guy told us he didn't know why it was doing it and didn't know how to keep it from happening again. We ended up paying him for the wood and the labor to install it and he walked away.

We then brought in another company (who had refinished some existing hardwood upstairs for us earlier last year and done a good job) to try to fix it. They sanded the floors down to the bare wood, restained (this time with a 50/50 mix of Minwax Provincial & Dark Walnut) and applied 3 coats of Bona oil-based satin poly. The 1st coat looked great, the 2nd coat showed lap marks, and the 3rd coat showed even more, as you can see in the photo below. They're coming out this afternoon to take a look but I'm hoping for some insight before they get here.

So essentially, 2 different crews using 2 different products have had the same problem. Based on info I can find online, possible culprits are: improper application and/or applicator (the 1st company used a pad and the 2nd used a roller), poly too thick or too thin, air temperature too hot/too cold, air blowing across the surface, etc.

Since it's cold, my first inclination is to think that it's an environmental issue - the first company thought maybe it was too warm in the house and the poly was drying before it had time to "flow". But could the floors be too cold even if the air temperature is warm? We have finished basement space below all of the floors but they're still cold to the touch.

If anyone has any ideas or suggestions that I could discuss with my contractor when he gets here today - I would really appreciate it! What's ironic is that we were SO afraid to do site-finished floors in this house because we've had so many problems in the past (not with poly but with stain and chatter marks). We'd planned to install prefinished floors instead because we didn't want to go through that again but we just couldn't find any that we liked (or that matched existing stained built-ins) and now this happens!

Anyway, thanks in advance for any help anyone can provide!

Leigh Ann

Follow-Up Postings:

RE: Help! Lap marks in poly on new floors!

What you're seeing is the differing distribution of the flatting agent that gives the finish it's satin appearance. The flatting agent is basically small particles suspended in the finish.
This looks like an area where the floor finisher was backing his way out of a hall, rather than applying the finish in long stretches. These marks show more with each coat as the floor gets smoother. They're more apparent with dark colors and lots of light. I'm not sure whether you could ever get it perfect but there are ways to minimize the appearance. A different coating strategy which allows you to coat an area using long runs, without backing your way out would help but might not be physically feasible. The poly needs to be stirred consistently so the flatting agent is distributed evenly. Air flow should be eliminated, and if possible, I like to have the area somewhat cool and humid so the finish sets up more slowly.
Other options would be to go with a shinier finish which has less flatting agent in it but I prefer the more satiny finish.
A water-borne finish might be better since it's formulated differently but it has it's own issues and doesn't wear as well. Plus it's generally recommended to wait until the oil poly cures 30 days first.
You probably won't like me for saying this, but you might have to live with this flaw. Adding more coats will only make the problem worse since every time it's buffed and coated, the floor gets smoother and the marks are more apparent. Sanding the floor again will likely result in the same outcome. Once you place the rugs and furniture and add some window treatments, this will be far less noticeable.
Maybe I'm too accepting of flaws, but as a realist, I acknowledge that nothing will ever be perfect. This was done by humans so it can't be perfect. There are so many things other than lap marks that can go wrong with floor finishing like big machine marks, edger marks, buffer marks, uneven stain, holidays, streaks, drips, puddles and trash in the finish. When a floor gets to the point where it's 95% perfect, it's unlikely that's you'll be able to get it any better. An improvement on one front can be offset by a flaw on another. And let's be honest, even if you could achieve a perfect floor, once it gets some traffic it will inevitably get some scratches and scuffs and the perfection is gone.
So how is the finish other than the lap marks?

RE: Help! Lap marks in poly on new floors!

Thanks for the long and thoughtful response JFCWood! But I'm having trouble understanding how 2 different crews, using different application methods, as well as different products, could end up with this same unusual result. It makes me think it HAS to be something unique to this environment. We've had hardwood floors installed and/or refinished in several homes before - always with a similar stain color and oil-based poly - and we've never had a problem with marks like this. As I mentioned before, crew #2 refinished some existing hardwood upstairs back in Sept. without incident. Also, as you can see in the new attached picture, the marks are everywhere - throughout the entire first floor and in wide open spaces - not just in the more confined spots.

What do you think about the hot/cold issue - either of the floor and/or the room temperature? And could the poly itself have been too cold? It was left sitting in our mudroom that's not currently finished and it's about 50 degrees out there. Both crews had us set the thermostat at 69 degrees and the heat was allowed to cycle on and off throughout application and during drying. I read a suggestion somewhere today that said to run the heat at 72, turn it off 30 minutes prior to coating, and then set it to come back on 2 hours later (assuming you have a programmable thermostat). Maybe the movement of air caused the poly to dry too quickly? Or was it a "stirring" issue since all of the marks are more "matte" than the rest of the floor?

Our guys didn't come out today after all to look at the problem but they'll be here on Saturday. I sent photos and they said they could clearly see the marks. They've suggested buffing and recoating but as you said - I don't think that will improve anything. We also have some pretty pronounced chatter marks that weren't present until the 2nd refinishing so there's a chance we'll be sanding down and starting over. We've had some experience having them removed and so we're not too worried about that but this poly issue is baffling! And believe me, we've been "just living with" a whole bunch of things since we're so far behind schedule on this project and have been living in 2 rooms upstairs for 6 months without a kitchen! But this floor was one of the most expensive line items in our remodel and we've always had beautiful hardwood floors and so we're reluctant to just let this go because they really are THAT bad. Thanks again for your input! Any more thoughts or suggestions?

RE: Help! Lap marks in poly on new floors!

You said they used a roller? Is that for that last picture too? The last picture kinda looks just like bad form when spreading finish.

Just a question about the darker stained floor. Do you have radiant in floor heating?

RE: Help! Lap marks in poly on new floors!

Greg - The pic is of the first job and they used some type of a pad/mop. I didn't actually see it but my DH said it looked like something you'd use to scrub your car at the car wash! But to be honest, the marks were virtually identical after each job - even though they used different applicators. And no, we don't have radiant heat.

RE: Help! Lap marks in poly on new floors!

Interesting - that looks like a spot of uneven application I have from my diy job last summer. One minor spot is one thing - but all over the floor? How disappointing - and you don't want to keep sanding your wood over and over. Where are you located and when did this happen - Our floors/walls here were bone chilling to the touch here in Wis this past week while air temps inside the house OK. I am not a pro but it would make sense that cold COULD make anything oil thicker and not flow or level as it should. I know Bona has a technical help 800 no - maybe you or your floor person could call?

RE: Help! Lap marks in poly on new floors!

kashka _kat - that's what I'm thinking too - something to do with the temperature. I'm in Louisville, Ky and the weather's been crazy this past month while the floors were being done. With the first company, temperatures were pretty normal (highs in the 40s/lows in the 30s) so I'm not sure they were a factor. But the 2nd time around, all was well until the 3rd coat of poly, which was done last Sunday morning (Jan.5). It got down to 18 degrees on Sat. night, warmed up to a freakish 56 during the day on Sunday, and then continued to drop for the next 24 hrs. all the way down to -3 on Monday night. And as I mentioned in my original post, the poly itself was probably cold when it was applied. Good idea about contacting Bona - I'll suggest that to them!

RE: Help! Lap marks in poly on new floors!

Yikes! That looks way worse than I thought. It's definitely over the line of what's acceptable.
I'd look further into the temperature aspect and at humidity. We use lambswool applicators for oil poly and apply the finish in long narrow runs rather than in short wide runs.
It gets harder to get a perfect coat as more coats are applied so it would be best if the next coat works. It would be ideal to have at least a two person crew to apply. One would apply the poly to the field of the floor while the other cuts in the edges, keeps the poly stirred, moves the bucket and watches for drips, puddles and holidays.
From your pictures I don't see the chatter marks but I do see a bit of dishing in the soft grain in your first picture. It might look worse in person but if that was the biggest flaw in the floor (i.e., if you were able to get a uniform poly coat) I'd be inclined to call it done.

RE: Help! Lap marks in poly on new floors!

I wish the dishing was the biggest flaw :-) Below is a pic of the chatter marks . . . They're more pronounced in some areas than others but unfortunately the great room (largest room) is the worst! Would you consider these to be outside the realm of "acceptable" or is it just me?

RE: Help! Lap marks in poly on new floors!

Maybe a better pic . . .

RE: Help! Lap marks in poly on new floors!

And this is in the hall - chatter in the midst of the worst lap marks . . .

Update to: Help! Lap marks in poly on new floors!

Hi! I just wanted to let everyone know how our floors turned out . . .

The owner of the flooring company finally came out to look at the floors and pronounced them unacceptable. He proposed sanding back down to the bare wood and starting over - which is what we'd hoped he would suggest. The plan was to sand the floors at an angle and then follow with a multi-head machine in order to remove the chatter marks. They also wanted to water-pop the floors prior to staining in order to achieve a richer, deeper color and then re-apply 3 coats of satin Bona Woodline poly.

And the results were . . . GREAT!

The chatter marks are still slightly noticeable (at least to us) but are not objectionable. The stain color is beautiful - we used 2 parts Dark Walnut to 1 part Red Oak - since the previous mix of 50-50 Provincial/Dark Walnut had produced a pale, cool color on our white oak. It's a much warmer, richer color now and we love it!

For the poly application, we used our programmable thermostat to do the following:

Warm the house to 74 degrees 1 hour prior to application
Turn the air OFF as application began
Turn the air back on at 68 degrees 4 hours after application

They also took the poly home with them at night and took it inside to keep it warm.

I have no idea which, if any, of these modifications worked to resolve the problem but we ended up with a streak-free floor and we're happy!

We did have one problem though, that I want to mention as a warning . . .

Around 1:30am after the 1st day of sanding, we received a call from our next door neighbor saying that a large black bag in front of our house was on fire. The bag (containing sawdust) was sitting at the base of our front steps (and in front of her car) and apparently had started to burn spontaneously. She was about to call 911 because her house was full of smoke but her son (whom she'd also called) arrived just in time to keep her from doing so. It took us about an hour outside in freezing temperatures and snow to get a hose hooked up, break open the bag, spread out the sawdust and wet it down until it stopped burning/smoking. Both homes and everyone's clothes smelled strongly of smoke and everyone had to shower before going back to bed. The next day (also in the snow), it took another hour or so to shovel up all the debris from the night before and bag it up so it could be thrown away. Not fun!

Apparently, because the poly on the floors had been recently applied, it reacted with the sawdust and spontaneously combusted. We'd heard of this happening with stain-soaked rags but were unaware that it could happen in this manner. Very thankful the bag wasn't left in our house or garage!

Anyway, there's a happy ending to our story and we're so very glad we decided to allow them the extra time to make the floors right!

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