Grit Question: DA vs. Hand

[Stretch]

I've seen it mentioned a few times that someone will suggest one grit if sanding by hand and another grit if sanding with a DA sander? I think specifically someone said use 800 grit if sanding by hand and 600 grit with a DA. Does sanding by hand somehow necessitate a higher grit?

Thanks-Stretch

 

[rex]

From what I've seen DA paper is a grade or 2 courser.Feels that way and I can see the difference but I was known to be be wrong once or a alot