Orange rogue board, in middle of room, obvs (as per sods law ) needed a little more persuation so out came the super bleach... now very light so will need to colour down with LF spirit stain in shellac. After bleaching make sure you wash 5 or 6 times with fresh water and leave to dry, preferably overnight.
Gap filling. Fill the largest gaps with wood slivers and D3 PVAC, I have 6mm and 8mm reclaimed pine slivers, these are good for gaps around 4mm or more, remember to clean the gaps very carefully and really hammer them home. When the floor moves the slivers won't. You can't fill the smaller gaps with slivers.
Now I need to mix the two pack wood filler and adjust the colour, slightly darker looks better imho. I use Morrells 2 component wood filler. Their pine is almost white, so I find light oak and yew good for reclaimed pine, some of it Georgian in this case.
You cannot have too many filling knives.
A mixing board is great, I got the blue one from Chris Stevens about ten years ago, I believe Brewers are the only place you can get them now.
If you are sensitive you might want to use an A3P2 respirator, I use 3M disposable ones. I probably won't need it here as the client is sensitive so I picked up my volume air mover. This removes about 75kg of air per minute (that's not a typo) so should change the air in this large Georgian reception room about every 90 seconds.
I will fill most nail holes as these are quite large, plus other large holes, gaps and cracks.
I find it useful to go around and place coloured tape on filling spots as once the filler is mixed you have 3 to 5 mins in this weather before it goes off. Yes, inevitably you may still miss a spot or two, but much less than without tape (or marker pen)
After that it's sanding off the wood slivers, then filling the smaller gaps and holes, I use Lecol 7500 and sawdust which I try and colour to match. These boards have tons of woodworm, so, lots of filler and probably two fills in general, larger gaps and wormy areas probably three fills or more. Some of it will come out, but in will look and feel much better.
Looking great as always Toby! Was it a concrete floor they are going down on? And do you cut your own slivers from the wood you're working with, or buy it in?