A method and apparatus for conditioning and monitoring a planarizing medium used for planarizing a microelectronic substrate. Color channel separation may be performed to separate different color channels, such as red, blue and green. Injection of a diluent during the cell concentrate removal process permits more complete removal of viscous cell concentrates. In other words, the RC structure turns off the first set of transistors after transistor switching is completed. The continuously dense protective layer which is formed in accordance with the invention is even more reliable in preventing impurity particles or impurities from penetrating into spacers between the structures of the mask layer.