Nicholas,

 

I think the official answer is you don't have to sand, but I always do, just like you described.  I remember reading somewhere that sanding "excites the molecules" or something like that.  Sanding right before bonding is supposed to create a better bond.  I even go back and re-sand a surface if it's been more than 24 hours since the original sanding.

 

Maybe I just love dust!

 

Mike Easley

Colorado Springs