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HELP! Polyurethane won't cure

3046 Views 10 Replies 8 Participants Last post by  Knothead47
Okay so I used the Minwax oil based poly on my hard wood floors. It has been just over a month and they still aren't cured. Two of my rooms are cured but not my main room and hallway. I used the same cans and stirred them constantly as I was applying it. I can literally scratch them with my fingernail and I dropped something on them the other day and it scratched it terribly. I let the stain dry for a week before I put the polyurethane on. I waited 24-48 hours between each coat of poly and I made sure I coated them on days that were not humid. What do I do? I have no clue what I did wrong :(
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Hey, Emily; welcome!
Man, that's brutal! Sorry to hear about your bad experience.Wish I could offer advice, but all I've got is phone a hardwood floor contractor and have him redo with a commercial quality finish.
(Personally I've avoided Minwax products for decades, and I can't even remember why... :( )
Bummer Emily, you didn't do anything wrong, is this product made to be used on the floor. You might go to the place where you bought it and ask them what went wrong, or contact MinWax and let them know your problem.

Hope you get relief, and let us know how this all comes out.

I know recently the woodworkers are using acrylic instead of polyurethane. they seem to like it better.

floors weren't dewaxed???
cleaning agent contamination???
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some more answers from elsewhere...

The cans of poly might have been the same but how old they were and under what conditions they were stored might be the problem. Since they say that this is in just one of several rooms then I would say the product used in that room was old and/or stored improperly. It might be old because the store might not have rotated their stock correctly, if new replacement product was put out first instead of old product replacing sold product and new product replacing stored product then it could have been sitting there in the can and get past the usable date. They might have bought a large enough quantity that they got old product from storage.

Storage environment might also have to do with quality of product. If it was stored against an out side wall or in a unregulated warehouse and was subjected to cold or heat or both then it might still be in date for use but might have been damaged by the environment in which it was stored.

One more thought is the flooring they used it on. Did this room have the same flooring or was it a different flooring product that might be the problem. Is it leaching chemicals into the finish and keeping it from drying? I know some of the import flooring has been band from import after it was found to contain excessive amounts of formaldehyde. Is it possible that this flooring is some that was imported before the ban?


There are a number of possible causes

- Finish is no good (as described above)

- Wood is different - might have something in it or just a wood that emits fumes that prevent finish from curing, cedar and teak are two examples

- Applied too thickly (does not allow oxygen to get to lower layers)

- Too cold (unlikely since probably adjacent rooms)

- Improperly prepared surface (did not say what he/she did to prep, was there an existing finish?) Stain applied too thickly (not wiped off) or incompatible.chemical
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Welcome to the forum Emily.

I just ran across the same predicament. I applied shellac first as a sealer and then the poly. The shellac was not dewaxed and I believe that was the problem. Applied a couple coats of sanding sealer and problem solved. If there was wax on the floor the same problem would arise.
Hi Emily and welcome. Oil based varnishes have driers added to them (for example Japan drier). The driers can either evaporate or degrade over time but this should only happen if the cans have been opened (usually opened a few times and left open while you apply the finish). Unopened cans shouldn't be a problem unless possibly they were badly out dated.

You say that some dried and some didn't. What if anything did you do differently in the rooms where it didn't dry?
Hi Emily, anytime I am applying a finish over an old finish, I wipe it down with mineral spirits to remove any wax and dirt. Then I apply wax-free shellac to seal the wood. I then use Zar polyurethane that I thin 80/20 with mineral spirits. It goes on smoother. I know this isn't going to solve your current problem. Malcolm / Kentucky USA
Great news! I called my grandpa's best friend who used to do a lot of hardwood floors and he told me he has run into the same problem before. He told me to lightly go over the floors (testing it first in a spot that wouldn't be seen) with mineral spirits. Well I tried that in a spot that wouldn't be seen and waited 8 hours and I have noticed a significant improvement in the hardening of the poly!! I'm going to give it a couple days to be safe before I do it on the entire floors. However, if this still doesn't completely solve my problem, can I try that sanding sealer and put it on top of the poly? I was a little confused on the one post that suggested this. Also, I would like to clean them up (I have only been dust mopping them cause I was nervous to use cleaner on them) but what kind of cleaners are safe to use on newly finished floors??
You might call grandpa's friend to see how he solved this problem in the past, in addition to the information he has already given. I'm getting to refinish stair treads. I used a poly and it wore off in no time. I got a can of Olympic Spar Finish (#04532) as it is used for gym floors I'm told.
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