I am looking for advice on waterborne finishes. I am in the process of building a dedicated spray booth. I had initially planned to set it up to allow spraying of oil based lacquers with an explosion proof fan, but in doing some reading on SMC I came across repeated endorsements of waterborne sprays including a lack of downsides. "Why would you spray OB." When I first set up my current booth I bought a QualSpray gun and EMtech8000. I recall reading (maybe incorrectly) that waterborne sprays need a shellac or other sealant as first coat to avoid raising the grain (for some woods, ?plywood), and that sounded like a negative to me. I have sprayed a number of mostly small projects (picture frames, clocks, etc) and have settled on an initial sanding prep using 220 grit, then 3 coats of EMtech8000, then sand with 220 grit, then a final coat. Sanding in between other coats has not seemed to make a difference for me. This gives a good but not great result. The finish is not as silky smooth as it was after my initial sanding prep. And the finish is not as smooth as when I brush on 3-4 coats of OB poly. Thus my interest in a spray booth that can handle OB.

My questions: 1) Are there really no downsides for the average hobby woodworker to spray WB, and 2) what am I doing wrong with my current EMtech spray process? Thank you.