I need to determine if a previous owner of my house had ever applied wax to a polyurethane finished fir floor. The reason I ask is that I would like do screen sand and put down a coat of poly to freshen it up. I have read that if the floor has ever had a wax applied that the new poly will not stick. The floor is still in "ok" shape, so I do not want to hire someone to sand to bare wood apply and do a complete refinish.

rub the floor in a spot with a white rag with mineral spirits. If it comes up just dirty then its not wax. if you get a yellowish goop that is most likely wax. A dewaxed shellac sealcoat like parks universal sealer is what I would do first to ensure the bond, then top coat with poly of choice.

Thanks KevinD the rag came up clean, so I went ahead with a light but thorough sand followed with a wipe with mineral spirits to get rid of the sanding dust and put down two coats of oil-based poly (Varathane Satin). Room looks much better.

One thing though is that there were a few spots where I missed a little bit of puddling in one corner and it can be seen in the dried finish. Would a dry-buff with a hand held polisher help?