Coat over pre-finished floor

Q: I just put hardwood floors, pre-finished, into my new condo. I love the color and grain of the wood I chose, but it is not shiny enough. My floor installer told me that adding polyurethane will only make it shine for around a month.

Is this true?

A: Most pre finished floors are either satin or semi gloss. Most manufacturers shy away from gloss, since the heavy shine shows scratches more than a lower shine. Most of such floors use an aluminum oxide or ceramic coating which is extremely hard. I would not even consider trying to apply a coat of finish over top of this. It is extremely difficult to impossible to abrade this finish enough to gain adhesion with a polyurethane applied in house.