While other brushes are primarily used by loading the brush with paint, the fan’s best use is clean and dry, softening and blending. A common use is to lay down color areas with other brushes and then using a clean dry fan brush with virtually no pressure, soften those marks slightly. This gets the brushwork going the same direction and can really push an area back into the distance easily. You might think you’re losing all that work you’ve done, but trust me on this.