As the demand increases for reprocessed resin from both post-industrial and post-consumer plastic products, a unique set of problems is encountered. Recycled materials may include unwanted components such as foreign contaminants, other types of polymer, and residual additives that may not be suitable for the intended application. In some cases, these components can lead to undesirable performance or odors. Post-consumer recycled material is particularly challenging because the history of the material is unknown, and the resin could include such foreign material as cleaning products, paint, or food products. Molecular weights can also be affected by incorporation of regrind material. Changes in molecular weight can have a large effect on mechanical and physical properties, such as strength, permeability, and crystallinity, which can affect the quality of the finished product. Through several real-world case studies, this presentation will cover many of the methods that are used to probe these types of issues to enable successful utilization of recycled materials.