I wish I could have gotten more images during Pratt's demos but there was constantly a swarm of people around him. So much in fact I don't really know how he did the first one, I think its just a graphite drawing underneath with ink brushwork on top.
The second technique is pastels with Gamsol. The Gamsol is used as a blender, turning the pastel dust into a wash. Gamsol is one of many solvents available, I've seen this done with turpentine as well, but I would not suggest it because it isn't the best for your health.
These two demos are courtesy of George Pratt.
Anyone who has information on these two demos please feel free to add :]