Can present with slightly pale, smooth or roughened surface morphology. Rumble strips are roughened surfaces that are either embossed or recessed. The foil is roughened by electrochemical etching to enlarge the effective capacitive surface. The surface is roughened to improve adhesion. The metallic substrate is roughened by abrasive blasting, then sometimes electric-arc sprayed with stainless steel. The surface varies from highly polished to considerably roughened. For the best bond, surfaces should be roughened (or scratched) with fine or coarse sandpaper. The bark is light gray, roughened by small warty lumps. The anode is highly roughened to increase the surface area. Finally, the surface becomes roughened with the glass anchored into the holes. Whale barnacles usually settle on patches of roughened, calcified skin called callosities. The front of the snout is highly roughened, being punctuated by many foramina. The lining of the gynecophoric canal is roughened by minute spines. Alternatively, beginning with a smooth plate, areas are roughened to make them darker. The metal where niello is to be placed is often roughened to provide a key.