I’ve been struggling with a fundamental problem concerning stonework, namely that unless it is polished it has a fine grained roughness. Very hard to add in ZBrush without having an insane poly count.

I looked at Substance Designer a while back and noticed that most of their materials use multiple normal maps. So, I created a noise image in PS, converted it to a normal map in xNormal, and used a colour combiner node in Vue to add it to the normal map I had baked from the high res sculpt. Result is shown above – much better than what I had before. Very happy.