A method of monitoring surface status and life of a pad by detecting temperature of a polishing interface during a CMP process. A difference is mapped between spectral measurements of a printed color generated by the color printing device measured at a first or hot temperature and at a second or cool ambient temperature where the mapping comprises a referenceable characteristic of the color printing device. The device also includes a cathode cleaner and a bottom up stacker assembly for stacking zinc sheets. Intermediate parts of the contact pieces in an extending direction are curved radially inwardly, and the curved parts of the contact pieces resiliently contact and hold the male terminal. Because the \u201chot\u201d and \u201ccold\u201d arms are joined together at their ends, the increased length of the \u201chot\u201d arm as a result of its thermal expansion causes the actuator bodies to flex, as a result of which the gripper portions of the gripper arms move closer together. The selection may be random, based on past user responses, or responses of users belonging to particular clusters.