Rob,

Good question....when you push it, you need to grab some bottom clay first in your blade so that you build a "ring" around the muck to hold it in place. Also, note that it takes this stuff a good while to dry out before you can work it. Mine never did really dry out completely but got to a point where I could push it into a very nice island. With the clay ring, it stays put. It was a great solution for me.