A hardwood floor can last 100 years if it's well cared for. As a professional, you know that refinishing the floor is one of the ways to keep hardwood floors looking warm and beautiful. Here's a step-by-step guide to refinishing a hardwood floor.
Assess the Floor
Make sure you know what type of wood you're dealing with when you get ready to refinish a floor. It's relatively easy to refinish a true hardwood such as oak or maple. If the floor is pine, it's a little more difficult to deal with, but with care, you can create a beautiful floor. Engineered wood floors, however, typically aren't good candidates for refinishing, as the veneer on the top comes right off as soon as you start sanding.
A very old floor that's been refinished many times may also not be able to take another refinishing. Pull up a heating grate if possible to see how much hardwood is left. If there's less than 1/8 inch above the tongue or if you can already see nail heads in the floor, you can't re-sand it any longer. Check out options for removing the old finish chemically to try to refinish the floor.
Prepare for Sanding
If the hardwood floor can handle another sanding, plan to be aggressive about it. Start with 36-grit sandpaper for a floor that hasn't been sanded in a long time or that has a lot of heavy finish on it. Floors that have been painted may even require you to go tougher and use 24 or 16-grit paper. Maple floors are so hard that they often require 36-grit sandpaper as well.
Pull up all the heating grates and any old carpet tacks before you sand. You can leave the baseboards in place unless you're planning to replace them. You need a pristinely clean floor before sanding, so sweep it and then dust mop it to get up all debris and dust. Make any necessary repairs to gouges and cracks in the floor before sanding.
Sand and Buff the Floor
Use a drum sander for your first sanding pass on the floor. Sand the center of the room first, and then finish with an edger. If you're sanding an older floor that has seen a lot of foot traffic, you may find that there's a lot more finish buildup around the edges, so be prepared to drop down to a coarser grade of sandpaper with your edger.
Wear a respiratory mask while you're sanding, since the process raises a lot of dust. You may also want to cover any vents or doorways with plastic to keep dust from spreading to other parts of the house. Wear safety gear, since splinters can fly anywhere.
Sand with the grain unless you're working with a floor that is extremely damaged or uneven. If you do sand at an angle to the grain, be aware that you're removing a lot more wood than if you were working with the grain. Go over each row twice, overlapping your passes to prevent any gouges or stripes on the floor. Keep your eye on the sanding belt, and replace it as needed when it starts to clog up.
The goal of your first sanding pass is just to remove the finish. Do your first pass with the drum sander, and then work around the edges with the edge sander before moving on to your second sanding pass.
In your second sanding pass, your goal is to remove any remaining finish and get rid of any scratches made by the first sanding pass. Use an 80-grit or finer sanding pad for this pass, and then repeat with the edge. When you're through with this pass, your floor should look like new wood.
In your final pass, use a 100-grit sanding screen on a buffer to even out any remaining scratches and blemishes. Once again, work back and forth, overlapping each pass. Keep the buffer in motion at all times to avoid leaving any marks. You can use a random-orbital sander to buff the edges.
Choose the Finish
The hardwood floor finish you choose determines the look of the floor. An oil-based satin finish gives the floor a warm glow and hides any imperfections while also bringing out the grain. If you choose this type of finish, make sure to allow for plenty of ventilation, because the fumes are far from healthy. A somewhat simpler option is a water-based finish that dries clear and doesn't produce the same volume of toxic fumes. This finish is an ideal choice for a homeowner who wants a floor that resists yellowing and doesn't require much in the way of maintenance.
Some homeowners may prefer to apply natural oils or waxes to their floors. These are especially good choices in historic homes, because they can take extra coats over time without sanding; an older home that doesn't have much thickness left in the floor may require this type of finish. Because they're nontoxic, these hardwood floor finishes are also safe for kids' rooms.
Apply the Finish
Use a foam applicator or bristle brush to cut in the finish around the edges of the room first, keeping the layers thin and even. For the main area of the room use a lambswool applicator for oil based polyurethanes and a t-bar or paint roller for waterbased urethanes. Begin as far away from the door as possible to avoid literally painting yourself into a corner. Work in 5-foot swaths, and keep moving. Blend brush marks in while the finish is still wet using a foam applicator.
Let the finish dry for at least 24 hours; water-based polyurethane dries a bit quicker. Then check the floor. If the finish has raised the grain of the wood so that it's no longer smooth to the touch, sand the floor lightly once again before your second coat. Make sure to dust mop and remove all dust before applying the second coat.
After you apply your second coat of finish, let the floor dry for anywhere from one to seven days.
Screening and Recoating
Another option for refinishing wood floors is screening and recoating. This simpler process can save homeowners time and money, but it's not appropriate for all floors. Floors that have been waxed or pre-finished floors coated with aluminum oxide coating really can't be recoated.
Think of recoating as a type of regular maintenance for a hardwood floor rather than a real refinishing. Screening and recoating involves removing the old coat by abrading it with a floor buffer instead of doing a full sanding, and then adding a new layer of water-based polyurethane. This process, while not a full refinish, can keep floors looking clean and fresh without taking off too much of the top layer of wood. Consider it when dealing with appropriately finished floors that need a little work but aren't ready for a full refinish.