Gap filling is a procedure which goes on most of floors at some stage of their life, there is two main most widely used methods available for filling gaps on wooden floors.
First method is dust and resin mix: we mix fine dust produced from the sanding process with either solvent based or water based filler. We use water based filler Bona Mix and Fill to avoid the strong smell of the solvent based fillers. When you mix the dust with the resin, stir to form a paste then we start applying it on the floor and filling the gaps. This method is suitable for filling gaps up to 5 mm.
Second method is using reclaimed pine slivers: This method is for filling large gaps between the floor boards. We applying Bona adhesive on the slivers then knocked them into the gaps, after 18 to 24 hours we sand off the excess material. Usually the result is better than the first method.