Hello, I've been finishing two beech butcherblock tabletops for a desk I'm making. I have applied 4 coats of gloss oil-based poly to the bottom with 1 coat of satin oil-based poly as the final coat. The sheen of the satin is very consistent across the whole piece, but there are plenty of dust-nibs and imperfections (no brush marks though). In order to get rid of the imperfections I went over the whole thing with some 0000 steel wool, but it didnt really knock down the imperfections very much and applying enough pressure to get the nibs out with the wool causes spots that are obviously very different in sheen than the rest of the piece. I've read that I should wet sand with 400, 600, 800, and so on until I reach the sheen I want (satin) using soapy water as lubricant. Finally I read to use 0000 steel wool to apply a paste wax or wool lube (not really sure what this does). Should I try to take the satin coat off before rubbing it? Does the process I put for rubbing seem correct? Also, is it difficult to achieve a uniform sheen by hand like with the satin poly or should I just accept the imperfections and move on?
One final question, one of my tables has developed a concave warp, I'm guessing from only finishing one side so far and the unfinished side drying out from my exhaust fan pulling air over it. Should I just finish the unfinished side and wait a few weeks and hope the warp goes away or should I try to fix it some other way before I apply poly?