I have some very gracious friends who are remodeling my bedroom. They laid an 1 inch poplar wood floor. Per recommendation of "the wood guy" I put a coat of Minwax sanding sealer and have put 3 coats of Minwax Polyurethane for floors. I have since learned that I could have used better products, they should have put a harder floor down, etc., etc... but I was just going off of the recommendation and my friend was kind enough to cut and lay the floor for free. So my question - is this enough or do I need to apply a fourth coat? What do I need to do from here? This is my bedroom floor but I do have 11 and 8 year old boys that can be a little hard on things. Thank you so much for your help.

If you have a decent build of finish, there is nothing else to be done. Unfortunately, the poplar will dent easily. More finish will not prevent this from happening.

Thank you...

How many coats depends on a lot of factors.

1. has the finish been thinned
2. method of application
3. how thirst is the wood

If you are thinning a finish, its obvious to most people that you need to apply more coats. it's a lot less obvious that the method you use to apply the finish also has an impact. Imo brushing on a finish allows for a much thicker coat than wipe-on or spraying, though brushing is a lot harder to do correctly. Wood absorbs finish differently from species to species and some times even tree to tree. I think the best methodology for finishing is test pieces.

When it's time for a re-do take a look at Last N Last. I used it after finding a lot of good recommendations for it. It's tough stuff. More expensive than Minwax and some of the others.