Polyurethane Nightmare


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Old 03-02-19, 05:42 PM
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Polyurethane Nightmare

I have older hardwood floors that needed a new coat of poly. I applied it -- long story short, it went on extremely thick, uneven, and patchy, even with a lambswool applicator. I should have brushed a THIN coat on without a doubt.

What is the best way to remedy this once it fully cures? I can use a rougher sandpaper and sand it down, but I'm hoping I can smooth everything out by brushing over everything with mineral spirits ... Is this possible? What is the easiest way to smooth the finish?

(Note: This is an older home -- I'm not looking for perfection, professional sanding, 40 hours of labor, etc -- just for hopefully a decent protective finish on a tired floor done by a VERY tired Dad).

Thanks to all.
 
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Old 03-02-19, 05:50 PM
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Knowing exactly what brand and sheen of Poly may be helpful. Whenever I've botched a poly job I've made it worse by putting something over it. Fortunately, the floors that I have done came out OK, so I can't offer the best advice, but you may want to let it dry well and sand it smooth and recoat.
 
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Old 03-02-19, 05:51 PM
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Hope you stirred the can. You always need multiple coats, so if you only have one coat on, give it plenty of time to cure, lightly sand it with 180-220, clean the dust off and repeat until you have 3 or 4 coats on.
 
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Old 03-02-19, 05:53 PM
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Thanks for the reply. Minswax Quick Dry Poly (oil-based) Satin.

Is sanding poly quicker than thinning everything down with spirits, you think?

Yes, I did gently stir the can for a minute with a paint stick.
 
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Old 03-02-19, 05:56 PM
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I don't know where you are getting this mineral spirits idea. The process is to let it dry and sand it until you have removed any imperfections, then coat it again.
 
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Old 03-02-19, 06:06 PM
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Ok. Spirits idea came from it being so patchy, thick in spots and barely visible in others.
 
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Old 03-02-19, 06:16 PM
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Should I opt for a coarser sandpaper at first because of the thicker spots? I don't know how easily poly sands down, but I sure am hoping it's easy!
 
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Old 03-02-19, 06:17 PM
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Sanding and more coats will even it out. When you apply it you might need to be more careful about working quickly and keeping a wet edge. That means you don't brush over areas a second time if they are already getting sticky. Working with the grain back and forth while backing out of a room.

180-220 grit. You aren't sanding it off, just smoothing it. You sand every coat the same way.
 
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Old 03-02-19, 06:35 PM
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Will do, thanks! ..............
 
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Old 03-02-19, 10:39 PM
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I'm hoping I can smooth everything out by brushing over everything with mineral spirits ... Is this possible?
No. You can thin poly with mineral spirits before use but poly is like concrete in that it doesn't actually dry, it cures. This is a chemical process which results in the final material actually being slightly different than the applied 'wet' material. Dirt/mud and a lacquer finish would be examples of materials which dried instead of cured and thus which could be altered by application of a solvent after the process was done.
 
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Old 03-03-19, 12:03 AM
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Minswax Quick Dry Poly (oil-based) Satin
For future reference, Minswax is a very low quality product, especially for floors there are much better products on the market!
 
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Old 03-03-19, 03:57 AM
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Mineral spirits might could have been used to even it out some BUT that only works while the poly is still tacky .... and how would you reach it all without standing on the tacky poly.

Often when refreshing a tired floor one coat of poly is sufficient, unlike raw wood that needs 3 coats. To fix it you need to sand, both for adhesion and to even out the blotchy finish. Hard to say sight unseen but I'd probably use 150 or 180 grit. As mentioned above always sand with the direction of the grain! You need to stir the poly well and you can thin it slightly if needed. If the poly isn't a fresh can it's a good idea to strain it.
 
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Old 03-03-19, 05:36 PM
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I sanded the crap out of it tonight. Several times with both medium and fine sandpaper.

Tomorrow I'm going to thin a new gallon of poly just a little and brush it on. It looked quite a bit better dry (or very close to dry) than wet yesterday.

I do think one more round of sanding and a final coat will do it ... my back doesn't like sanding ...
 
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Old 03-03-19, 06:01 PM
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Minwax poly is so runny I can't imagine thinning it even more. I also can't imagine putting poly on an entire floor with a brush. You will be going so slow that the floor will be full of brush strokes as it will be getting sticky before you make it from the end of one side of the room to the next.

Also "sanding the crap out of it" wasn't anything that any of us suggested, so thats on you. You typically just need a very light scuff sanding between coats. An average sized room would literally take no more than 5 minutes to sand.

Hope it turns out well for you.
 
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Old 03-04-19, 03:20 AM
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I recently did a floor with 1 gallon and 1 quart of Minwax poly and I was surprised that the quart was much thinner than the gallon - they should have been the same. Other than the first coat over raw [stain] wood I rarely thin poly but if it's too thick to go on correctly thinning it a tad is in order.

I agree a light scuff sanding is all that was likely needed. IF you sanded thru the poly an extra coat might be needed.
 
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Old 03-04-19, 05:49 PM
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Got a new coat on today. 700 square ft took about and hour and a half to brush. I like the brush because it keeps it even. The lambswool is what originally made one heck of a mess. What do you normally use?

Tomorrow I'm going to do a quick sand like you suggested with 220. Then one more coat of straight poly stirred very frequently. Will post pics.
 
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Old 03-05-19, 03:42 AM
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Lambswool pads work great although if the hardwood isn't sanded smooth enough or otherwise has something that can grab the pad they won't work as well as they should. Before they came out with the pads floors were always brushed - usually with a 6" or 8" brush. Providing you can keep a wet edge a brush will do a better job albeit a lot more effort.
 
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Old 03-05-19, 02:52 PM
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Doing one more coat. Would anyone recommend Varathane over Minwax?
 
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Old 03-05-19, 03:01 PM
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I think their quality is about the same, both on the lower end of the floor coating scale.
 
 

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