Hi Tommy just stumbled on this topic and I find using Revell acrylic number 9 Anthracite as base coat and I have a graphite pencil block bought from hobby craft that I file with a nail file and dry brush this powder in once dry. I find it gives a varied metallic look like for instance a rifle barrel is powder coated and scratchs wear and tear look convincing. I also use the same technique for undercarriage weathering