Hi mate, I've used paint brush bristles in the past with good results. I buy a cheap 4 pack of those big broad brushes you use to paint walls, verandahs, etc. from my local hardware store... and they'll cover a lot of space on your groundwork.
I've also read, fairly recently, about using frayed bits of string. I haven't tried the string thing yet, but the paint brush bristles definately work. Just make sure they're clumped together nice and close and you'll be in business. Cheers.