Q: After refinishing a hardwood floor hallway with coats of polyurethane, there is a white cloudiness on some parts of the floor that will not wipe away or go away. What can I use on it or how can I repair it?
A: Was this a waterborne polyurethane? It sounds like you didn’t allow previous coats to dry thoroughly before applying the next. This white cloudiness in the finish is called “blushing”. It may go away on its own as the coatings cure.
Floor white after coating with polyurethane
Q imported from our old site, Face Lift Floors: “I stained the floor and allowed it to dry then put the polyurethane on it, which made the floor white, and in some spots, the stain came off. Why?”
A: I will make an educated guess here. The only time I have seen such a chemical reaction is from combining 2 dissimilar chemicals when the first one applied has not properly dried. I have seen this when polyurethane is applied over lacquer sealers that have not dried. (I don’t use such sealers myself.) If the stain is not actually dried, then when you apply the first coat of polyurethane, It can actually “pull” enough of the stain from the surface to make the color look lighter and blotchy.
As a representative of a major stain and floor finish manufacturer recently said: “your finished product will only be as good as the first coat of finish“. What he meant was that if proper drying has not occurred, It can spoil the rest of the job. Things such as the problem you mention, or the finish actually pealing from the floor surface, if not right away, then soon.
Original / moved link https://faceliftfloors.com/q-and-a/stain.php