I look through a lot of portrait photography on the web (usually Pinterest now) for things to draw and over the past few years I've come across a lot of black and white portraits in this sort of "show every wrinkle" sort of super-sharp, high contrast closeup. I'm embarrassed to say that I don't know where the trend comes from. If you do leave me a comment.
In any case, I wanted to try rendering one and I thought it might be a good match to use a very scratchy looking bristle brush. I turned the opacity all the way up and laid out a set of color steps to sample from as a way to force myself not to keep overworking things. I think the study still looks a bit overworked. Next time I'll force myself to use a larger brush as well. But I do like the scratchy texture. It gives things a bit of energy.