After the floors are sanded we mix filler and fine saw dust to create a mixture with which the gaps between boards are filled. In this video you find out how this is done.
We usually go over the floor twice with this gap filling procedure to make sure it really sets it. We also gap fill large gaps with pine slivers which you may notice in this video. 0203 397 4145 http://www.stepflooring.co.uk