Okay so Wet or Dry is a good brand for this, and I want to do it wet through the whole process? I figure David knows what's best to make a Square-2 for obvious reasons. I just got bored of my MF8 Square-1 so I started cutting corners in half.
As it happens my change to wet sanding happened when fixing masters for the Gigaminx
, many years after the Square-2 work I did.
For that I sanded dry but would sand wet if I were doing it again. Water contains the mess of powder you otherwise get, and keeps the paper from clogging as much. I even forgot (until I re-read the link above) that I used to get friction blisters from dry sanding. I just don't see any advantage to dry sanding.