Posted by Peter on 09 Sep 2012, 20:05
I've seen a trick today, but I'm not sure if it's what you like to know.
Cover the places you want mud on with a dark wash.
Sprinkle with a big brush pigment over the wash (let it fall, no dipping)
Let it dry a bit and whipe of with kitchen paper.
He showed this on a piece of road, and it looked very good. I will try it myself one day!