In this review, a simple conceptual model for xerographic developer charging is used as a framework to illustrate key aspects of toner aging. Topics covered include: the effect of toner additives (external/internal) on charge level and charge admix; the effect of toner physical properties such as concentration and size on performance; the impact on toner aging of external factors such as toner throughput rate, relative humidity and process control strategies.
Robert J. Nash, "Toner Aging: Causes and Effects" in Proc. IS&T Int'l Conf. on Digital Printing Technologies and Digital Fabrication (NIP23), 2007, pp 221 - 229, https://doi.org/10.2352/ISSN.2169-4451.2007.23.1.art00054_1