Do you know what the diastic power of your 6 row is? Even if it is 180 L, 4 lbs isn't quite enough, that's why your mash was gooey, not enough enzymes for a good conversion. With all grain mashes after a good saccrification, you should have your grain suspended in liquid (watery) and they should seperate easily. If you give it a little time the grains will settle a lot and you'll have a good amount of liquid on top. Generally with a 11lb/5.5gal mash, after settling I can get 2 gal of liquid before I get to the grains. A mash of predominately corn is the only AG that won't settle out very good. Also, a paint strainer bag make seperation easy, much more so than a pillow case.
"Necessity is the plea for every infringement of human freedom. It is the argument of tyrants; it is the creed of slaves." William Pitt