If you have gaps in your floor boards that are over 3mm wide then pine slivers is the option for you. All slivers are made out of reclaimed pine and eliminate any draft coming up through the gaps. 
 
The wood slivers are glued both sides using specialist adhesive and then wedged in to the gap- once dried they are cut flat to the floor before the sanding process is resumed.
 
For smaller gaps, we also have the choice of using a special resin which is mixed with the sawdust collected from the sanding process. We then spread the mixture into the gaps and once dry, we sand off the excess and continue with the flooring.