Brush skimmers are oleophilic skimmers that pick up oil on the bristles of a brush. There are two main configurations for the brushes: drum brush skimmers, in which the brushes are mounted around the perimeter of a drum; and chain brush skimmers, in which the brushes are mounted on several continuous loop chains. In each case, the brushes are rotated through the oil/water interface, picking up oil and some water. The recovered fluid is then combed from the bristles into a sump. Both brush skimmer types are generally used in an advancing mode. Chain brush skimmers are typically configured with the skimmer head facing aft, creating a calm area for oil to accumulate and be recovered, reducing the skimmer's sensitivity to waves.