Special caution should be taken when exposing plugs decorated as such to moisture. While my jewelry is selected to be fully functional in everyday life, including cleaning, bathing, and swimming, go easy on those with inlays or a combination of materials. Certain metal jewelry may cause reactions in sensitive individuals, and may include nickel allergies or discoloration of the skin. This may be removed with a hand polishing cloth or with a buffing wheel. Tightly wrapping all-cotton thread around the area of metal being worn will keep the skin out of contact with the metal, as well as increase diameter of the wearing surface of a weight being worn, which helps to distribute the pressure more proportionally.
Wood forms the circulatory and support system in trees.
The grain you may see running up and down in hardwood plugs is what the tree used to transport water. When the plugs get wet, they may try to absorb the water, and the cells that form the grain can swell. This can make them feel less smooth than when new. The plugs are sanded, then washed , then sanded again after they dry to take off any of the cells that are going to swell up when in contact with water. This process is repeated several times.