I’m going to refinish my hardwood floors; what grid sandpaper should I use and what type of coating should I put back on the hardwood floors?
Refinishing hardwood floors is a popular project that can really improve the look of your space. If the finish is just dull and there aren't deep gouges or any other kind of serious flaws in the floors, the simplest way to prep the surface for a fresh new coat is to rent a floor buffer with a sanding screen. The screens gently rotate to take off only the top layer of finish and won't damage the surface underneath.
If the floor is badly damaged, you'll need to rent a floor sander. Typically, there are two types of floor sanders available. A floor belt sander is the tool most pros use. These tools are big, heavy, hard to maneuver and if you sneeze when you are using one, can damage your floor for life. We don't recommend renting a belt sander for your floors. If they are that bad, hire a pro to do the sanding. Nothing short of using one of these behemoths every day is going to give you the experience to use one without making the floor look worse than when you started.
A better option for the DIYer when refinishing hardwood floors is a machine known as a U-Sand. A U-sand is a 4 disk random orbital sander that does a fabulous job sanding the floor and is goof-proof regardless of the skill level of the user. It also does a good job of sucking up the dust it creates, making for a much neater job and smoother finish.
Even with these tools, you will most likely still need to do some sanding by hand in the areas tough to get to. You can also rent a disk sander that is designed to get into the edges of the floor, but keep in mind that these machines typically leave swirl marks that may none the less need to be hand-sanded out.
Polyurethane is the finish of choice for floors. The finish is available in both latex and oil based versions. In our experience, the latex finish works well for cabinets, trim and furniture but just doesn't have the abrasion resistance to do a good job on the floors. For refinishing hardwood floors, oil finish still delivers the best long term result.
When refinishing hardwood floors, the best way to apply oil-based polyurethane is to "mop" it on with a synthetic "lamb's wool" applicator. This useful tool, available at any home center, looks like a sponge mop and lays down a silky smooth finish in a fraction of the time it would take to do it using a brush. For best results, use several thin coats and try to avoid heavy traffic on the floor for a few days after the finish is applied so that it can fully harden on the newly refinished hardwood floor.