April 17, 2009

Sanding Hardwood Floors

Preparing to Refinish a Hardwood Floor:
1. Inspect the floor carefully. Most oak floorings are 3/4" thick and can be sanded a number of times.  Remove a floor register if possible, and measure the thickness of your flooring. If it is thinner than 3/4" you should consult a professional floor refinisher. Thinner floors must be refinished with the utmost skill and caution to avoid sanding through to the subfloor.
2. Try to remove the shoe molding, if applicable, so that you can sand all the way to the wall.
3. Inspect the floor carefully--tighten any loose boards and pull out or counter-sink any protruding nails or staples. Sanding exposed nails can produce sparks, which creates a fire hazard in the sander!
4. Check fuse supply as sander may overload the circuit in an older building.
5. Provide adequate ventilation.
6. Cover arches or doorways with a dropcloth or plastic covering. Stuff towels under bottoms of doors and cover all air vents.
7. Sweep the floor clean immediately before sanding.

Renting a Sander & Purchasing Sandpaper:
1. When you rent a sander, be sure you get the manufacturer's instruction manual and some hints and/or a demonstration from the store where you rented it.  Be sure you also have any attachments, special wrenches and dust bags needed. Floor sanders are powerful machines and if not used properly can quickly gouge your floor beyond repair.
2. Purchase a dust mask and ear plugs if you don't already have them.
3. Purchase the appropriate sanding discs, sheets or belts to go with your sander(s). An average room will require 10 sheets, discs or belts of each grade. If you will be sanding more than one room, it is worth it to call ahead of time and order from a sandpaper supplier like www.abrasiveresource.com rather than the rental store. If you are only sanding one room, the quantity of paper needed is small enough to just buy the sanding supplies right from the rental store.
4. If you are refinishing an old floor and need to remove paint or sand cupped boards, start with a coarse grit like 16 or 20 grit and then move onto the 36 and 50 grit paper. If you are sanding an older floor that is in good shape, you may start with a 36 grit to just remove shellac or varnish. If you are sanding a new floor, simply begin with the 50 grit paper.
5. Your next sanding will use an 80 grit  and the final sand can be a 100 or finer grit. 
6. For a professional looking finish, use 2 different types of sanders--a large sander for the main area of the space and a smaller edge sander to get up close to the walls.

Sanding Hardwood Floors:
1. It's a good idea to practice first with a piece of your fine grit sandpaper just to get the "feel" of how your sander works. That way, as you are getting used to the process you are less apt to make a heavy gouge in the wood. When you feel comfortable, switch to the coarse grit to get started.
2. Your first process in sanding uses the coarse grit sandpaper. You are removing any previous stain, finish and discoloration as well as leveling the floor to a smooth surface. If the floor has warped boards or ridges where two boards come together, you may need to sand diagonally across the floor until smooth and then sand with the same grit again with the grain of the wood to get the sanding marks left by the diagonal sanding out.
3. Be prepared to change your paper regularly. The heat from the friction of sanding melts any old finish and this clogs up the sandpaper, making it ineffective. If you start to notice that the sanding rate is dropping, your sandpaper is probably clogged or worn out. Stop sanding and change your paper. If you continue operating with a worn out or clogged sanding paper you will eventually burn or damage your floor!
4. Follow the instructions for your particular sander. Let the sander pull you forward at a slow, steady speed. You can sand both forward and backward, but always keep the sander in motion.
5. Sand two-thirds of the floor in one direction(with the grain), then turn 180' around and sand the final third of the room with the grain. Overlap your back-and-forth passes to be sure you are sanding all areas thoroughly and to assure an even, blended finish with no sanding marks. Go forward and then return over the same area as you go backward. Move sideways in 3" or 4" increments to overlap each pass. Do not attempt to remove 100% of the old finish during this operation. Small residual amounts will be removed during your subsequent passes.
6. It's a good idea to vacuum the floor between each grit so that you aren't sanding random pieces of the coarse grit paper that may have shelled off during sanding into the floor with your next finer grit.
7. After you have done the main part of the floor with the rougher paper, use either a rented edge sander or an electric vibrating sander to sand where the floor meets the wall and in any other areas missed by the big sander using your next grit in the sequence.
8. After your 50 grit sanding, fill all dents, gouges and cracks still remaining with a commercial wood filler that is easy to sand and will accept a stain. If you have large areas that need filling, you will have to do this process twice, as the filler will shrink a bit when it dries. Allow extra time here for the filler to dry...
9. Now use your 80 grit paper to smooth the latex floor filler and remove the scratches produced by the 50 grit sandpaper. 
10. Hand sand all the areas your electric sanders could not reach--inside corners, around door casings and jambs, up to cabinet kick plates, etc.
11. Time for your final sand using a 100 or 120 grit sandpaper.
12. Vacuum the floor well--to be extra sure all the dust is up you may want to tack the floor clean with a paint thinner soaked towel wrapped around a push broom or swiffer. Now you are ready to finish!

If you have questions or comments, please call Abrasive Resource at 800-814-7358. We supply floor sanding supplies from our warehouse in NY and can drop ship to addresses anywhere in the United States.

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