I recommend you get as close a weave burlap as you can find, something like the burlap bags are made of. I didn't really pay attention when I bought mine, the weave is more open than I would like. Next time I will pat attention to the weave. It will work fine, but I would like a closer weave.
When you are up to your butt in alligators, it is hard to remember your intent was to drain the swamp. Stay focused!