Originally Posted by Bills Brew
I've read that you aren't supposed to squeeze the bag, as that will release some undesirable tanins.
I've read this too, but:
At the local BOP I started at (before I decided to do it at home) they made me squeeze every last drop out of the grain bag. It didn't give the beer any harsh tannin flavors or astringency. In my opinion, the jury is still out on this one.