How to sand a wood floor

Sanding wood floors - Bona

Your floor needs to be sanded in stages with progressively finer abrasives for the best finish. Starting with grit 40, then grit 60 and finally grit 100 is tipically a good procedure for most wood floors. The goal with the first coarse abrasive is to remove the old surface coating and to flatten the surface.

Tip: Have a good look at the floor. If it’s very uneven or has a tough, sticky coating, you may need more aggressive abrasives. Gradually progress with finer abrasives in small steps to ensure you remove the scratches made by the previous abrasive.



Coarse sanding

Attach the coarse abrasive to the sanding machine. If the machine has variable pressure, set it to high pressure. Make sure the sanding drum is raised from the floor before starting the machine. Start the motor. Slowly release the sanding drum towards the surface.

Tip: Move softly. It’s important that the sanding drum is always lowered and raised while the machine is moving. Imagine an airplane softly landing and lifting.

Start to the left of the room and sand in the direction of the wood. If the floor is very uneven, we recommend to sand diagonally. Walk slowly forward and lift the drum gently as you reach the wall. Lower the drum again and return in the same path that you sanded. Lift the drum and create a new path to the right. Overlap about 5-10 cm on the previous path.

Once the whole section has been sanded, turn the machine around and sand the other end of the room. Repeat this process until the floor is flat and all residues from the old coating have been removed. Always empty your dust bag before it is completely full to ensure the most optimal dust collection.


How to coarse sand a wood floor - Bona

Edge sanding - Coarse

  • Attach a grit 40 abrasive to an edger and start sanding in one of the corners.
  • Move the machine in small circles going from left to right.
  • Don’t place any body weight on the machine, just let it do the work.
  • Sand until all old coating has gone.
  • Empty the dust bag.
Coarse edge sanding wood floors - Bona

Medium sanding

Medium sanding:

  • Set the drum sander to medium pressure and attach a grit 60 abrasive.
  • Start sanding in the opposite corner and follow the direction of the wood.
  • Move slowly and return in the same path that you have sanded.
Medium sanding - Bona

Edge medium sanding

Edge medium sanding:

  • Check that you have emptied the dust bag.
  • Attach a grit 60 abrasive and sand the edges of the room to remove scratches and smooth the surface.

Tip: If you plan on filling gaps in the floor with a joint filler later, you will need some of the wood dust from the sanding. Empty the dust bag and be sure to collect only clean wood dust. Put it in a seperate container for later.



Medium edge sanding wood floors - Bona

Corner scraping and corner sanding

Now it’s time to remove the old coating from the corners. It’s most efficient to start by scraping off the majority of the old coating with a scraper. Finish off by sanding with a fine sand paper. 

Corner scraping wood floors - Bona

Gap filling

You don’t always need to fill the gaps in the floor, but it gives the surface a finer, more professional impression. The joint filler is intended for small gaps between 0.1 – 2 mm and on floors that are dimensionally stable.

  • Shake the Bona Gap Filler container and mix its contents with the wood dust you collected from the medium edge sanding. Either do this directly on the floor or mix it in a separate container which might be easier. The typical mixing ratio is approx. 1 part wood dust to 3 parts filler. Try to achieve a consistency similar to yoghurt.
  • Pour the mix onto the floor and distribute it with a stainless steel trowel. For best filling, apply diagonally to the wood direction. If the mix becomes too thick and hard to work with, add more filler to lower viscosity.
  • If there are gaps across the whole floor, use a wider spatula.
  • Let dry 30-60 minutes, if the gap is large then the filler may slump, in that case it will require a second application.

Tip: Joint filling is not recommended for large cracks, plank or end-grain floors, or parquet with bevelled edges.


Gap filling wood floors - Bona

Edge sanding - Final

  • If you have used gap filler remove any residue left. Do this at the same time as the final sanding.
  • Start with the edges, attach a grit 100 abrasive to the edge sander and sand all the edges of the room.
Final edge sanding wood floors - Bona

Fine sanding - Final

Finally remove the filler and fine sand from the rest of the floor using the drum sander with abrasive grit 100. Sand systematically and ensure there are no remaining filler residues.

Final fine sanding wood floors - Bona

Extra sanding – for oiled and hardwax oiled floors with a single disc machine

If you plan to protect your wooden floor with varnish, then sanding is ready at this stage.

If you will use oil or hard wax on your floor, then we recommend an additional fine sanding to achieve an even finer surface. This is because oil and hard wax oil tend to highlight abrasive scratches. Use grit 100 on the edges and grit 120 for the main surface.

Tip: Use an eccentric sander on edges and in front of doorways for a perfect finish.

Extra sanding oiled wood floors - Bona