A method of preparing a cellulosic article includes a step of combining cellulosic material and binder resin to form treated cellulosic material. There may be more than one active region per cell allowing more than one bit of data to be stored in each cell. The insert has an outer periphery that conforms to the shape of the groove and has an inner periphery that conforms to the shape of the metal roof seam. Further provided is the monitor unit employing narrow, widely-spaced, fast rise-time, fast transition-time pulses for conductivity measurement and alarm activation.