The accelerated aging processes of experimental handsheets in dry and humid gases at 90° C have been followed by measuring changes in their blue and green reflectance, the derived whiteness and yellowness indexes, the moisture regain, and the sonic moduli. Decreases in reflectance are shown to be closely similar in rate to losses in tensile strength, which is in partial agreement with the published results of earlier workers. The wet strength of these papers when aged in dry gases can increase, while their reflectance is nearly constant, or in humid gases, the wet strength may initially increase and then rapidly decrease while their reflectance is continuously decreasing. Thus, there is no evident correlation between wet strength and reflectance. Differential thermal analysis of the untreated, deashed, and Altreated papers in dry nitrogen gave principal decomposition endotherms above 300° C. -- AATA