The next step consists in separating the oil from the rest of the olive components. This is done by centrifugation. Centrifuges separate the oil, the water, and the solids separately. In most cases, the oil coming out of the first centrifuge is further processed to eliminate any remaining water and solids by a second centrifuge that rotates faster. The oil is then left in tanks or barrels where a final separation, if needed, happens through gravity. This is called racking the oil. Finally the oil can be filtered, if desired.