Polyurethane wrinkling due to environmental issues?

Q: We had our floors refinished, and the second coat of polyurethane bubbled and cracked everywhere we had oak (there was pine in the kitchen). The first coat went on fine, but the second coat looked awful. The contractor said it was our fault because the baseboards were off so it was too humid (they were off before they started). We fixed the baseboards, put foam in the cracks to the exterior, turned on the heat for a few days, and they are still having trouble.

The guy said he would sand it and re-do it one more time and then abandon the project because it’s an environmental problem not his problem. Is there nothing else we or he can do to make this work?

A: What do you mean by cracking? Do you mean it has raised edges that look a bit like alligator skin? If so, this is called wrinkling. It is caused when a coat of finish is applied over a previous coat which is not sufficiently dry. The solution would be to make sure it is warm enough for a typical finish to dry over night. That would be 70 degrees at least. High humidity can also slow drying. It’s winter. I wouldn’t think that would be an issue. The floor would have to be well dry and then aggressively screened with a polisher and abrasive screen pad. That is assuming I am understanding what you describe. I find it hard to believe not having the baseboards in place is responsible for this. The first coat went on fine as you say. So, it sounds like there was a reaction between the first and second coat as I mentioned above.

Follow-up Q: Wrinkling sounds right. When the first coat went on Wednesday two weeks ago it was like 60-70 degrees with low humidity (Houston, TX) and then when the second coat went on Friday the temp dropped and there was a lot of rain/humidity. They scoured off some of the wrinkled coat of polyurethane yesterday and then put another test coat on yesterday after we had the heat on and it started wrinkling almost immediately.

He said he’s going to give it a few more days with the heat on and do another test of polyurethane and if that doesn’t work he’ll go with a wax finish instead (as opposed to abandoning the project now..). I think you’re probably right about the first and second coat reacting, but it sounds like this is the first time this has happened to that guy in 10 years and he doesn’t really know how to handle it. I’m a little nervous about the wax finish, but we really just need to get into the house and I’m sure it’ll look nice.

Thanks for your feedback! I was finding it hard to believe as well that there were “environmental” conditions that he couldn’t work around.

A: If it is going to wrinkle it will happen immediately. Is there a basement under this floor or a crawl space? I’ve heard Texas is really getting punished. Flooding, and then major snow storm? If you have cold air coming from under the floor it can take several weeks to dry unless you have a heated floor or a heat source under the floor. He may need heat and a bit of ventilation also because this means there likely is still a small amount of solvent left in the coating. While not always the case, generally if the finish is dry enough to recoat it will powder when the first coat is buffed. If it isn’t dry enough the finish will roll off as tiny clumps.

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