1.1 ,This guide describes methods for characterizing the efficacy, under prescribed laboratory conditions, of a brush part designed to clean the external surface of a medical device. The method utilizes force testers to mechanically actuate a brush part across a surface at a constant rate and constant pressure. In the first method, the force required to actuate across the surface is measured. In the next method, which utilizes the same force testers and protocol (actuation motion), the brush part is actuated on a soiled surface and the amount of soil removed is measured, as another indicator of performance.