Care and Storage of Calibration References - D19c / D196 / D 200 II

To maintain the calibration of a densitometer, the calibration reference must be properly maintained. Improper care or storage will render the calibration reference questionable or useless. Even if properly cared for, calibration references change over time. It is always a good idea to maintain a replacement schedule for densitometer calibration references. For reflection references, it is good to replace them at least once every year. For transmission references, replacement every two to four years is sufficient, provided their integrity has been maintained. Calibration references should be stored in their original protective sleeve in a dark area. Placing the reference in a desk drawer is not uncommon and is acceptable provided care has been given that it will not become damaged. Placing it within a file folder that is kept with other important files is a good way to store it. This will keep the reference from the light while maintaining its flatness. Heat and humidity will also alter a calibration reference over time. The storage area should not experience extremes of humidity or temperature. Generally speaking, if the environment is comfortable for people, it will be acceptable for the calibration reference. Calibration references should seldomly be cleaned, if at all. Most cleaning agents leave some type of residue which can compromise the integrity of the calibration reference. For ink or paint on paper references, normally used with reflection densitometers, simply dust off the reference. Do not use any liquids to clean it. If the reference has become soiled or damaged, it must be replaced. Film calibration references, used with transmission densitometers, should only be dusted with a soft camel’s hair brush (available from most photographic supply stores). The use of film cleaners will alter the values assigned to the film reference. Ceramic on metal plaques used with reflection densitometers should only be cleaned by applying a moist breath to the surface of the plaque and wiping it with a clean soft cotton cloth. If cared for properly, the calibration reference will maintain its usefulness and ensure the measurement integrity of the instrument for which it was intended.