In one embodiment, a washing system including a nozzle assembly having a nozzle and having formed therein a rinse passageway and a waste passageway. A nutplate having a threaded mounting portion is adapted to threadedly engage an externally threaded filter head. The broom head has a leading edge that is flat and at an angle that is roughly perpendicular to the bed of the shovel head. The protrusion pattern gives a variation range of chromaticity coordinates on a chromaticity diagram dependent on an angle of view.