Wet-sanding

You should anticipate that it will take about four or five applications of three coats each (and subsequent wet-sandings) before the parts are finished.

When your primer coat is dry, it's on to the wet-sanding to get that paint flat and silky smooth.

The stock pores should be filled by this 400-grit wet-sanding with just a trace of finish left on the surface. One more wet-sanding with 600-grit paper is done, leaving almost no finish on the surface.

Wet-sanding with a damp sponge works well too.

Wet-sanding is done either with regular sandpaper that's been wetted or with a dampened sanding sponge.

Using a large sponge to wet-sand drywall joints will definitely reduce dust, but wet-sanding isn't feasible for a project of any size because you must rinse the sponge and change the water continually. Also wet-sanding soaks the paper facing, sometimes dislodges the tape, and tends to round joint compound edges rather than taper them.