I have an old, quarter-sawn fir floor in my kitchen and dining room, in dire need of refinishing and no extra wood left to sand. Floor finishing people always liked to grind away all old finish, but I’ve thought that a bad idea, unless damage to wood had to be dealt with. In the past [10 years plus], on other floors in similar condition, I would first use TSP, but could not find a final cleaner that would adequately remove old wax and silicone residue, at home paint supply stores. Instead, I looked to the automotive paint stores for cleaners, since contaminants are the bane of automotive paints, with good success. My question: Does anyone know of any cleaners now available which might be better suited to prep house floor finishes? Also — the last finish was an oil-based clear finish. This time, would a water-bourne urethane work? Better?