The first 2 tests it sounds like you lost more than you'd probably be comfortable with, but the last test sounds more encouraging. All the same material I assume?
I'm not a dirt guy by any means. I was advised to make a ball, about the size of a baseball, maybe a little smaller. I put this into a bucket of water and let sit for 20-40 minutes. When I took it out very little had fallen off the ball into the water, the outside was greasy, the inside was dry, and when I split it apart it became 2 whole pieces. I was told this was good stuff. Don't know if you'd like to give that a try as well, though your methods sound pretty good as well.
Good luck and an expert should be along to give you more opinions shortly.
