We replaced 30 meters of boards that were rotten or missing with reclaimed floorboards. We sanded in several stages, starting with 36 grains of sandpaper until the level of the boards was leveled and the worn surface was removed, then we continued with 60, 80 until the surface was polished. We also made a gap-filling with sawdust and resin. We finished with satin lacquer 3 coats.
