in the embodiment of fig4 such an arrangement permits the creation of multiple wear sectors on a single inclined surface of the roller 801 by permitting removal inversion and reinstallation of the same roller 801 midway through a useful life that may be twice that of a conventionally oriented roller this may be possible for example and as is apparent from fig8 since each edge corner tends to produce a wear sector at a unique location along the slope of a given inclined surface of the roller 801 such that inversion and reinstallation of the roller exposes unworn or u201c fresh u201d friction surfaces to each of the edge corners in other embodiments such as shown in fig9 multiple edge cleaning rollers 801 may be inventively oriented at one of two preferably equal and opposite angles to the plane of rotation of the wafer w e g for balancing of out of plane forces imparted to the wafer w by the angled rollers finally it should be understood that the inventive edge cleaning rollers described herein are each independently inventive and may be employed in apparatuses other than those adapted to scrub a wafer 39 s major surface further as will be apparent to those of ordinary skill in the art the inventive rollers may be employed to clean the edge of a wafer supported in any orientation e g horizontal vertical etc thus the inventive edge cleaning rollers may be advantageously employed in a vertically oriented scrubber such as that disclosed in u s pat no 6 575 177 the entire disclosure of which is incorporated herein by this reference.