i used GE silicon II. (black&grey). but i didnt apply it first, but with the dirt. i mixed it into a mudd and smeared it like plasture.it was messy and wasteful though in my opinion. *sigh* but it gave of a cool effect because i could press in more dry eco earth to give it a tutone effect. if your interested in that you can check my viv build thread.

http://www.frogforum.net/vivarium-te...ighlight=build hope this is helpful. =) good luck bud its fun and i imagine you will make another lol once you finish one the ides keep flowing!