Polyurethane for wood floors...Problem please help!!!?

Question

My husband and I have been working for about two weeks trying to save an old hard wood oak floor in a house we just bought. First the previous owners GLUED a carpet on the wood floors so we had to scrap all the glue up and we sanded, sanded and sanded some more. We finally got the base coat of polyurethane down and I think two more coats of Minwax Polyurethane for floors down. We got to the step where we are supposed to sand the floor a little before we apply the third coat. As we were sanding the polyurethane started peeling off the floor!!!! My husband had a big ball of it in his hand that he had pulled up off the floor. Why did this happen and how can we stop it and save all of our hard work? We decided heck with the sanding and heck with the 3rd coat and just reaplied poly in the section that peeled off and left it for the night. Was this the right thing to do? It has been very humid up here in Pa the past few days so we thought maybe it wasn't drying correctly. Thanks for any help

Answer 1

This is because as you said "it's been humid" that's your whole problem. Humidity and heat.
You did the right thing, two coats are plenty and, if it's not necessary, you don't need to sand. Good luck.

Answer 2

I am truly believing you are applying way too much in a single coat, this is preventing it from drying correctly.
You see, you should barely have the tip of the brush wet when you apply it. it should not be dripping but just barely wet - and only on the tip. Do not "Dunk" the brush right in and you're supposed to tap the brush to the side of the can to remove excess.
Keep in mind, when it comes to finishing wood " Thinner is always better" which means, the thinner the coat is you apply the faster it will dry, and the better your end product will be.
When I apply finish my coats are really thin - often you can barely tell it is even wet. However, the coats build up and in the end it looks great.
Have you sanded with the correct grit paper? I'd start with about a 100 Grit to remove all the crap then go to about 150 Grit, and since it is a floor there seems to be little need to go any further- after all, its not furniture your finishing. I'd still do the steel wool #0000 to knock down any raised fibers before applying my finish " In Thin Coats."

I would sand " Very Lightly " between coats - Maybe a 220 Grit, but remember to use Tac Cloth to get up all of the sand debris - otherwise you will see that in the end and it will look crappy 'cause of this.
Personally, I would want to make sure my coats are dry- so I would allow a bit more than the stict 24Hrs, maybe wait until mid-afternoon to apply the second coat if the previous coat was applied in the AM.

Once I'm down to doing my final coat I no longer sand between coats, that is done between coats up to this point. Keep in mind too, the three coats is a standard, but not a strict law that the 'Finishing Police " will hunt you down if you violate it. If you feel you need a fourth coat then do a fourth coat - it will strengthen your hard finish in the end. It will make it look a lot better anyway. I had a few situations that required more than three coats only - on one job I had to apply a fifth coat but that is "Thin Coats" like I said do not apply thick coats it is not pain or stain it is a finish and those methods of application no longer apply.
This is my thoughts on the topic, and if you do have a spot that came up just apply more to that area until it is even with the surrounding area. Poly will fill in but it may take several coats to get back to where you were - then continue on from there- which may be an additional coat on the entire floor.

Answer 3

Polyurethane For Floors

Answer 4

Ain't it fun?

Sounds like the top coat didn't dry completely. The poly that I used said you could add a coat without sanding within 24 hours. More than that needed a light sanding. If I knew then what I know now I would have done the sanding and hired the pros to come in and put the poly down.

Sorry I don't have any ideas to help you with the part that came up. I sanded one part down to the wood three times before I got it right. good luck.

Answer 5

When you apply more than one coat "sanding" is not the proper method. After applying more than one coat you must only "buff" the 2nd or 3rd or 4th coat. Buffing in a sense is sanding but with a much finer paper. Your problem is that hubby let it get to hot and it gummed the paper. Yes? Let it get hard for a couple days. Work on something else. Go to the Home Depot and rent the buffer and buy the pads. Go over the whole floor with the buffer and wipe it down with mineral spirits ( I recommend low odor mineral spirits sold in the paint dept.) then apply the final coat with a lambs wool. You guys will love the outcome.

Answer 6

It sounds like a bonding problem with the wood. If the wood was originally waxed, there may still be some wax residue on the wood. Did you apply a cleaning solution before beginning with the base coat?

Another problem may be with the polyurethane being contaminated, or not having dried enough before the second coat went on. It depends on releasing solvent to the air as it sets up.

In cases of high humidity I can see the solvents not evaporating as fast, then the next coat seals in the first one before it has cured to a good bond with the floor.

Speak with the vendor and see if waiting a week or so might help with the curing before sanding.

Answer 7

Think you didn't let it dry enough. Also, Home Depot rents a sanded called a "no-brain-er sander" It's more like a buffer than a sander. You do need to put the poly down very thick, with a lambs wool pad, almost like mopping it on, but LET IT DRY! The coats need to be sanded with a screening pad, like a screen door screen. Then clean them very well with mineral spirits. Apply second coat. Then do all over again, etc. Sounds like it didn't dry enough, or didn't get totally clean between coats.

Answer 8

Polyurethane was a bad choice for such an old floor.

You should have used shellac or tung oil.

You will need to start over again.

Also---sand those only floors sparingly or you will be staring at thousands of little nail heads.

These old floors are not like the new ones.

Try getting it off with denatured alcohol then shellac or tung oil as I said.

Answer 9

I just put 2 coat stain looks good today I put down 1 coat polyurethane and now is turning olmost white spot why

Answer 10

Sounds right to me. About the not drying right part. I think that was your problem. Let it dry for a few days or more. Set up fans to blow on the floor constantly.