My deck has been done with Thompsons waterproofing twice over the past several years and looks nasty. I have pressure washed it and would like to stain it with a Minwax stain. I would like to use a polyurethane as a sealer. Would this work and what about a lasting effect. Does polyurethane stand up to walking traffic? Any help here would be appreciated. Or do you have any other comments. Thanks