Sentence:  The stock pores should be filled by this 400-grit <WSD>wet-sanding</WSD> with just a trace of finish left on the surface. One more <WSD>wet-sanding</WSD> with 600-grit paper is done, leaving almost no finish on the surface. 
Meaning of the word marked with <WSD> tags:  Sanding with fine-grained sandpaper and lubricant.