These knives are replicas of actual knives found at an ancient Celtic site. It has been made by a blacksmith speciaizing in re-creating historical artifacts using historially accurate methods. As such you may find carbon on the blade. If you plan on using your knife you can clean this off with water and wire wool. Be sure to dry the knife thoroughly as the knife is made from Carbon Steel wich will rust. Protect the knife from rusting by applying a coat of oil to it. If you plan on to use your knife on food be sure to use a food safe oil.