Since the inception of more modern recycling, rules governing acceptable items have somewhat evolved. This is generally due to more improved procedures for recycling collection, as well as more improved processes as the raw commodities get turned into new items.Although caps on plastic jars and bottles used to have to be removed before recycling them, the Plastics Recycling Industry (APR) asks that caps and closures be kept on plastic bottles and containers at the point of recycling."

