Abstract: An apparatus and associated method are disclosed for the treatment of a surface through the projection of an abrading material against the surface. The abrading material is fed from a hopper to a centrifugal blast wheel which projects the abrading material toward the surface, the blast wheel rotated by a blast motor. A controllably positionable valve is disposed between the hopper and the blast wheel to regulate a rate at which the abrading material passes from the hopper to the blast wheel. During operation, a target current to be applied to the blast motor is determined by a control circuit, the target current indicative of a desired rate of abrasion of the surface. The control circuit then measures the current applied to the blast wheel and controls the position of the valve in relation to the target current and the measured current.