Post-Industrial Polypropylene Material: Plastic that was never used by consumers is referred to as post-industrial. This extra plastic is a byproduct of production and is produced for a number of different reasons. Some scrap is created when goods are contoured or when manufacturing is altered along a line. Other times, scrap is produced when essential inspections on the printing standards and product quality are made. This plastic can be simpler to gather and recycle because it never leaves the manufacturing environment.