Yes. Polyurethane must be sanded in between layers. You should use high-quality sandpaper to ensure that you get rid of all the particles that have accumulated when it was wet. It produces a much smoother finish and helps it adhere to each coat. Due to the fact that you require a minimum of 3 coats of water-based polyurethane to obtain a smoother and professional coating, you must stand in between layers. Sanding is not needed between layers for adherence, particularly if each coat dries out in less than 6 hours. It's advisable to recoat polyurethane on the exact same day. Regardless of all the products available nowadays, nothing beats how effective it is to stand in between polyurethane coatings. Yes, it takes time and a little cash, but it's certainly worth it for the results, In addition, it's the only method that is able to correct any small errors in the application and save you from starting the whole job again. Recommendation: When to Use Water-Based Poly Water-based polyurethane is excellent in most flooring applications, but I particularly recommend it over oil-based options when you’re refinishing maple or other light wood or when you want a perfectly natural look. Oil-based polyurethane almost always tinges the surface yellow, which can leave an unnatural or undesirable appearance. Some water-based poly will create a slight tint, but there are plenty of options that will dry perfectly clear and leave your wood looking natural, light, and beautiful.