Q: A floor contractor sanded our oak floors to the bare wood and finished them, leaving a lot of small grit and hairs under the finish, so he redid the floor, and it looked even worse after. On the third try his job satisfied us. He used an oil coat of some type and a water based poly for the final coat. I am not sure what his exact process was. However, after three months the finish started to blister, mostly starting in the cracks between the planks.
This is happening throughout a very large area in several places. What would be the correct way to fix this problem? Our General Contractor wants to have it buffed and one coat applied. Does this make sense?
A: I suspect the first coat he applied went between the boards and didn’t dry. Is this blistering or tiny beads of polyurethane? If the latter, this condition is known as poly beads or poly balls. You may have to keep scraping it off until it finally dries and stops.
If it is actual blistering, you likely have a reaction between the incompatible solvent in the initial coat (mineral spirits) and the water borne poly. In that case you may have to sand yet again. A clean environment and clean finishes are imperative to provide a good looking floor.