Thanks for your quick response, and your help again. After what you said and the follow up from Steve, I think I will go with Water based Polyurethane. Why flat??? And is there any thing that can be used in some of my gaps (top of the groove came off some planks when removing underlayment that was over the wood flooring). I was thinking of just slightly filling the gaps with a little clear caulk or strong polyurethane glue to seal the gap and then the finish just fill up the rest of it. What do you think of that crazy idea?