Hi all. We are self-renovating a 1970s property (our first). We found floorboards under the carpet, redwood pine in good condition. We have sanded them down (belt sander, to 180 grit). We filled with sawdust and a cellulose wood filler but got lots of shrinkage resulting in gaps and holes between the boards. We plan to ultimately finish the boards with OSMO for a natural and pale finish. I am stuck what to use as filler, do I keep doing more coats of the cellulose (have done two so far). I also read OSMO have a pre-mixed water-based filler. Would this dissolve in contact with water if it was coated with OSMO? Anyone got any experience of this? Not having to sand again would be great if possible!