An apparatus for processing a sample of fibers and trash, having a cylinder for receiving the sample. Pins extend from the surface of the cylinder and retain the fibers. A knife extends along the cylinder adjacent the pins, and removes the trash that is not retained by the pins. The trash is separated from the sample along a downward direction. A counter-flow of air in an upward direction is directed towards the cylinder, where the velocity is sufficient to blow the fibers that are not originally retained by the pins up toward the cylinder, and yet is insufficient to prevent gravity from pulling the trash downward.