You should recalibrate monthly, or as recommended by your plate supplier. If you can demonstrate good process control, recalibration should rarely be necessary. A good quality-control system will check consistency of media batches, UV exposures, ThermoFlex linearity, washout unit effectiveness, and consistency of plate and press results. Most consistency issues are a result of issues apart from workflow and ThermoFlex exposure—although it is a good idea to check linearity of the ThermoFlex weekly. If there is any variation in calibration or linearity, contact a Kodak service representative.