A process used to estimate the permanence of paper or other substrate. Depending on a paper's chemical composition, it can have varying levels of longevity. Since normal aging is not practical, procedures have been developed to simulate the aging process in a much shorter period of time. Accelerated aging uses either the "dry method," in which a paper sample is aged in a 105ºC oven for a set period of time, and examined for reduced strength, brittleness, reduced tearing resistance, folding endurance, etc., or the "moist method," which ages the paper at 90ºC at 25% relative humidity. The fibers of cellulose that make up a paper deteriorate more rapidly in the presence of moisture, so it is believed that the moist method more closely approximates the natural aging of a paper. (See also Permanence.)
|