I'm building a simple coffee table out of the last of my butternut. The top will be a glued-up panel of four boards, each about 7" wide. The table will be stained with Minwax dark walnut, with a few coats of satin poly to finish. Two of the boards have small knots, which will look OK, but I think they need to be filled a bit before finishing is complete. I suppose I could do it by applying a few extra coats of the poly, but I wonder if there is a better way. Any help will be appreciated. Thanks in advance.