Drawing Techniques: a Guide
Dry Media: Stump  
These are cylindrical tools made of coils of soft, textured substances like leather, felt, or paper. Artists rub their pointed ends over chalk, pastel, or charcoal to blur the lines and to create shading. Sometimes they are used only for local effects over small areas. At others, especially in chiaroscuro drawings, they are used extensively, almost like a drawing medium in itself.