Contamination

Also called: Foreign matter, impurities, black specks, cross-contamination

Contamination is any unwanted material in recycled plastic, such as other polymers, metal, paper, dirt or labels, that lowers quality and processability.

Contamination in recycled plastic means any material other than the polymer and grade you are buying. It is the single most common source of quality problems in recycled raw materials.

Common types

• Other polymers, such as PVC in PET, PE in PP, or HIPS in ABS.
• Metal pieces, wires and springs that damage screws, screens and moulds.
• Paper labels, glue, sand, soil, product residue and wood.
• Degraded or burnt particles that show as black specks.

Why it matters when buying recycled plastic

• Even small amounts of an incompatible polymer can cause weak spots, surface defects and processing failures.
• Contamination adds weight that you pay for but cannot use.
• Agree a measurable limit, such as visible contaminants per sample weight or maximum PVC content in PET flakes.
• Ask about sorting, washing and metal detection at the supplier, and inspect a representative sample before dispatch.

Use our recycled plastic quality checklist to set clear contamination limits in your order.

Contamination limits should be written into the purchase order and checked on arrival, with a clear agreement on what happens if a lot fails.