The well known technical and production benefits of polyethylene separator materials over other separator materials have prompted a dramatic increase in polyethylene separator usage in recent years. Separator trends in the United States from 1980 to 1996, and in Europe from 1987 to 1992, are shown. The manufacturing process for polyethylene separators is outlined, with particular emphasis on the latest advances in manufacturing technology. These improvements have resulted in a higher quality product, and also benefit the environment because of the sophisticated oil extraction and solvent recovery system. The product quality improvements resulting from the latest manufacturing technology include consistent conformance to dimensional specifications, low electrical resistance, close control of residual oil content, virtual elimination of pinholes, and good running properties on the battery manufacturers' plate enveloping machines. The material can also be manufactured with a very thin backweb to reduce electrical resistance still further.