A recycler can use segregation or controlled blending according to the actual process. The chosen model must be reflected in storage, line feeding, processing records and recycled content calculations; controlled blending is distinct from mass balance.
Must a recycler always physically separate certified material from every other raw material?
No. RecyClass Recycling Process Certification allows two chain-of-custody models: segregation and controlled blending. In segregation, certified recycled plastics remain physically separate from other materials. In controlled blending, they may be mixed with virgin plastics, masterbatches, additives or fillers, but the share of recycled plastics in Recycled Output must remain known and controlled.
1. Two models, two approaches to control
Recycling Process Audit Scheme v1.1 identifies segregation and controlled blending as the two chain-of-custody models. A recycler can apply under either scope according to the actual process.
The choice goes beyond terminology in a procedure. It must reflect how material is stored, fed to the line and processed.
2. Segregation keeps the material physically separate
Under segregation, certified recycled plastics are stored separately from other materials and clearly identified. Physical separation should also be maintained during the recycling process.
The scheme allows recycled plastics from different sources to be mixed where they have the same relevant characteristics. It does not allow virgin plastics or other ingredients to be added under the segregation model itself.
3. Controlled blending allows mixing in a known proportion
In controlled blending, recycled plastic may be physically mixed with other materials or substances, such as virgin plastics, masterbatches, additives and fillers.
The key condition is that the recycled plastics share in the final Recycled Output is known over a defined period, and that the input-to-output relationship can be demonstrated.
4. Controlled blending and mass balance are different models
In controlled blending, recycled plastic is physically present in the output in a known proportion. Mass balance may use different rules for allocating a material characteristic within a system.
The comparison between controlled blending and mass balance is covered in a separate article. Here, the focus is on the two models explicitly permitted in the Recycling Process scheme.
5. Minimum recycled content matters in controlled blending
The scheme specifies that recycled content in Recycled Output is calculated as the minimum percentage of recycled plastics. This supports communication of a specific percentage physically present in the product.
An average should not replace this result where some output has a lower recycled share.
6. Storage should support the chosen model
Segregation requires physical separation and clear identification. Controlled blending requires accurate records of each input stream, without which the proportions cannot be calculated reliably.
In either case, a shared silo, storage bay or material transfer must be assessed for the risk of losing material status or information.
7. Dosing and measurement are particularly important when blending
If the recycled percentage depends on dosing settings, scales or flow meters, the equipment and process records become direct evidence of recycled content.
Without control of these parameters, a company may know its planned recipe but be unable to substantiate the actual result.
8. When segregation may be simpler
Segregation is a natural option where a facility processes a uniform certified stream without adding virgin material and wants to maintain clear separation.
It may, however, require more separate storage areas and disciplined changeovers between production campaigns.
9. When controlled blending is a natural fit
Controlled blending suits processes in which recycled material is deliberately combined with other ingredients to achieve particular product properties. Examples include compounding and the production of Recycled Output with additives.
The model is flexible, but demands strong control of quantities and formulations.
10. How to document the choice of model
A procedure should describe incoming materials, certification status, storage locations, line feeding, the mixing stage, mass measurement, recycled content calculation and identification of Recycled Output.
The auditor should see the chain-of-custody model operating in the real process, supported by the documented procedure.
FAQ
Does segregation prohibit mixing two deliveries of recycled material?
Not automatically. The scheme allows recycled plastics from different sources to be mixed when the relevant characteristics are the same. Required information must still be retained.
Does controlled blending allow virgin plastic to be added?
Yes. Virgin plastic is one example of a material that may be mixed with recycled plastics, provided the proportions are controlled.
Is controlled blending the same as mass balance?
No. They are different chain-of-custody models.
Must the output percentage be known in controlled blending?
Yes. The input-to-output relationship and recycled plastics share must remain known for a defined volume and period.
Does the model affect the claim?
Yes. The chain-of-custody model determines what information about physical material content can reliably be passed along the supply chain.