Q: We attempted to apply a top coat of polyurethane on our old floor with a roller. It is full of bubbles. Will applying additional coats correct this?
A: You will have to rub this coat down really well to knock off the bubbles, especially so if they are fish eye type. Some finishes roll on very well but you must make sure there is no air movement across the floor for several hours after applying the finish so that it doesn’t set up too quickly and allows the finish to flow out smoothly.
Similar Q: Why does our floor have bubbles between most of the floor boards, after it was recently refinished?
A: Is this just bubbles or actually beads of finish on board edges?
Bubbles can appear if the solvent is evaporating too quickly. This can happen, for example, if there is a sky light or a lot of window exposure with direct sun light heating the floor. Best to cover the windows while coating.