We have moved into our new house in May and about a month ago some bubbles/ blisters started appearing on our hardwood floor in the kitchen, which has a water based polyurethane finish. The installer inspected and advised we had spilt something on it. We could not recall spilling anything however had to accept the verdict. About 6 weeks later we were away for a week and returned to find more blisters in another area of the kitchen. Again the installer inspected sending photos to the supplier of the polyurethane and advised us again we had spilt something on the floor. We are confident we didn't as after the first bubbles we have been so careful/ obsessive with not spilling anything, and two, we were away at the time. We live in a subtropical area and both times the blisters appeared was after a hot few days of weather - perhaps coincidental? Please see some photos here: https://www.dropbox.com/sh/d8btg6hjdwj1 ... wcuca?dl=0
Can anyone shed some light onto what may be the cause please?