In my most recent series of acrylics I developed a technique whereby I worked the gesso primer to create relief textures for the various elements in the artworks, followed by a series of washes to add definition to them. You can see this in the rendered concrete wall in Graffiti in the grime, Milsons Point, the concrete road texture in Buses Exc and the rock textures in F3 and other landscapes.
I had particular success with Buses Exc, where heavy splashes of wash looked remarkably like oil stains! And here's a tip: paynes grey is great for washes because it is made up of two pigments - a blue and a brown - which separate in curious ways as it dries! Both Buses Exc and Iceberg calving 2 were done with paynes grey alone.