Before the detail carving is done on the tree itself, the areas outside the circle are sanded smooth. The tree itself cannot be sanded, else it would loose all detail. Having smooth and rough surfaces on the same piece will help give the sections definition. During the finishing process, the oil will penetrate further into the rough surfaces than on the smooth surfaces. Because of this, each section will be a slightly different color, which will help distinguish the main part of the carving from its surroundings.