Abstract: One aspect of the present invention includes an apparatus for scrubbing substrates such as a roller scrubber. According to one embodiment, the apparatus comprises a scrubbing medium having an axial bore and a mandrel having a section disposed through the axial bore of the scrubbing medium. The mandrel is configured so that it exerts an adjustable axial compression on the scrubbing medium. According to another embodiment, the apparatus comprises a roller scrubber. The roller scrubber comprises a scrubbing medium comprising a plurality of discrete disks having a center hole. The disks are disposed side by side so that the center holes form an axial bore in the scrubbing medium. The combined outer edges of the plurality of disks form a scrubbing surface of the roller scrubber.