Added coat of polyurethane without abrading existing finish

Q: I have a 3/4″ oak floor 10 years old with a oil base ******** Polyurethane. I have lived here since the floor was installed and no wax has ever been used. Cleaned only with damp cloth of water and vinegar. Recently I cleaned floor with damp thinner cloth and about two hours later I applied a coat of the same Polyurethane as original used and a second coat six hours later.

The floor looked beautiful for about a month and then bubbles started appearing mostly where the boards join. I did not do any sanding, and mineral sprits may have not dried in the cracks.

A: The problem is not with the mineral spirits which should be compatible with most oil based polyurethanes. The problem is that you did not abrade the existing finish with a fine abrasive to create a mechanical bond. You have no bond between the coats and can fully expect this finish to peel off.It usually starts on the edges of the boards and spreads from there. These 2 coats of finish will have to be removed. Given the situation, I think you may as well go the full route and have the floors sanded and finished from scratch by a professional such as myself.