Last updated: 14 September 2026.
Quick answer: Two bottles can both say “50% recycled” and be built in completely different ways. Under physical segregation, only recycled material runs through the line, so the bottle in your hand contains it literally. Under mass balance, recycled and virgin feedstock are processed together and the recycled share is attributed to output through audited bookkeeping — the recycled content in any one bottle is a calculation, not a physical fact. Both models are recognised, both can be certified, and neither is fraud. What matters is that you know which one you are buying, because it changes what you can honestly print on pack.
Where this fits: This is the accounting layer under the PCR cosmetic bottles guide, which covers what PCR and rPET are and how certification works. Read this page when you need to interrogate a recycled-content claim rather than choose a material.
Why the same number can mean two different bottles
Recycled feedstock is not piped to a factory in an endless, segregated stream. It arrives in batches, from different recyclers, at different times, with different quality. Manufacturers blend it into production any way they can, and the industry has settled on two defensible ways of counting what comes out.
Physical segregation (also called physical segregation / closed-loop)
The recycled stream is kept apart end-to-end: separate silos, separate conveying, separate run. When the line runs, it runs entirely on recycled feedstock for that batch.
- What it gives you: the strongest possible claim. The bottle physically contains the recycled material. A brand can say “made from 50% recycled plastic” and every bottle in the carton is the same.
- What it costs: you pay for the segregation itself — cleaning between runs, separate storage, lower scheduling flexibility, and a thinner spot-market of supply that can hold it.
- When it is the only honest option: mono-material, single-colour programmes; premium sustainability lines where the claim is the product; any programme where a journalist might ask to see the material flow.
Mass balance (attributed content)
Recycled and virgin feedstock enter the same process. The recycler or converter keeps an audited ledger of how much recycled material went in, and allocates — attributes — that share to a defined portion of output.
- What it gives you: availability and price. You can buy recycled content when segregated supply cannot serve your volume or your colour.
- What it costs you in precision: an individual bottle may contain more or less than the stated figure. The 50% is a system-level average, verified by bookkeeping, not a per-bottle guarantee.
- When it is legitimate: when the certificate is issued under a recognised chain-of-custody standard and the claim is worded to match the model.
Why both are allowed
Mass balance exists because recycling does not scale without it. Segregated streams are limited by how much clean, single-grade post-consumer material can be collected and kept clean. Mass balance lets a much larger share of collected plastic replace virgin resin, on the condition that the arithmetic is auditable. The problem is never the model — it is a brand printing a segregated-grade claim while actually buying under mass balance.
The two models side by side
| Physical segregation | Mass balance (attributed) | |
|---|---|---|
| What’s physically in your bottle | The recycled material itself | A blend; recycled share is allocated |
| Claim strength on pack | Strongest — verifiable per bottle | Valid, but must be worded as attributed/system average |
| Cost | Higher — segregation, cleaning, scheduling | Lower — standard supply chain |
| Supply availability | Limited; tighter for colour-critical work | Broad; easier at volume |
| Audit trail | Batch-level, physical | Ledger-level, reconciled over a period |
| Best for | Mono-material, premium sustainability lines | Volume programmes, mixed-colour ranges, colour-critical SKUs |
| Biggest risk to you | Not much — mostly cost | Over-claiming on pack wording |
The practical rule: segregation buys certainty, mass balance buys scale. Choose the model, then write the on-pack sentence to match it. A claim that outruns its model is the single most common compliance failure we see in recycled packaging.
What “attributed” recycled content actually means
The word attributed is doing real work. Under mass balance, the recycled content is assigned to output according to a documented method — normally a ratio of recycled input to total input over a defined production period. A few consequences follow, and each one is a question worth asking:
- The claim is time-bounded. It is reconciled against a period, not an individual cavity or a single shift. Ask what period.
- The allocation method must be documented. Under the self-declared claims standard ISO 14021, mass balance arithmetic has to be traceable rather than asserted.
- **Attribution should reach your product.** A certificate that proves recycled material entered the factory is weaker than one that attributes it to the specific SKU you ordered. This is the difference between a scope-level statement and a transaction-level one.
- It must be reconcilable. If the recycled tonnage you buy is larger than the recycled input the factory actually purchased in that period, the arithmetic does not close — and that is exactly what an auditor looks for.
The documents that prove it
Four document families carry the weight of a recycled-content claim. Ask which of them your supplier can produce, and for which level of the chain:
- GRS scope certificate (SC) and transaction certificate (TC) — the mainstream chain-of-custody route for recycled content. The scope certificate establishes that a facility is certified to handle recycled material; the transaction certificate ties a specific shipment to recycled input. A TC per delivery is far more useful to a brand than a single PDF of a scope certificate — the mechanics are in our PCR and GRS explainer.
- EN 15343 — the European standard for traceability of recycled content in plastics; it is the backbone of several recycling certification schemes and appears in European regulatory expectations for plastic packaging.
- ISO 14021 — the standard for self-declared environmental claims, including recycled content. It sets what a claim must be able to substantiate.
- Recycler-level certification (e.g. schemes auditing post-consumer plastic recyclers for traceability and quality) — this is what tells you the chain is not broken before the resin reaches the converter.
If you only ever ask one question, ask for the transaction certificate covering the resin in your order. Everything else is context.
Five questions that settle a recycled-content claim
- Is the content segregated or attributed? Ask directly. A supplier who can answer this plainly in one sentence is usually the one with a working system.
- Which certificate, and at what level — scope or transaction? A scope certificate proves capability; a transaction certificate proves this order.
- Can the attribution be traced to this SKU? Not to the factory, not to the group — to the product.
- What period is the mass balance reconciled over? If nobody can answer, the ledger probably is not audited.
- Is the on-pack wording reviewed against the model? Attributed content needs wording that does not imply physical segregation. Our six documents guide lists the wider paperwork set that should arrive with a bulk order.
Frequently asked questions
Is mass balance recycled content greenwashing?
No — it is a recognised accounting model used by certified supply chains, and it is what makes recycled volumes replace virgin resin at industrial scale. It becomes greenwashing only when the claim wording implies physically segregated content. The failure is in the sentence on the pack, not the ledger.
Can I claim “100% recycled” under mass balance?
You can claim a recycled content share that the ledger supports, but a “100% recycled” claim on a mass-balance bottle is a wording risk. If your brand needs to state 100% without qualification, buy segregated material and accept the cost and lead time.
How do I tell which model my supplier used?
Ask for the transaction certificate and read the wording: certificates issued under chain-of-custody schemes state the model and the period. If the document only says the facility is certified, you have a scope statement, not proof for your order.
Does mass balance change the quality of the bottle?
No. Both models use the same recycled feedstock and the same molds. Mass balance is a bookkeeping method, not a material change — appearance, drop strength and processing behave the same way.
Why is segregated PCR more expensive?
Because the premium is in the logistics, not the resin: separate storage, cleaning between runs, tighter scheduling and a narrower supply pool. You are buying certainty of physical content.
Which model should a first PCR project use?
Start with attributed content under a certified chain of custody, at a moderate percentage, while you validate colour and processing on your own molds. Move to segregated material for the SKU that carries your sustainability message publicly — see the percentage decision in our 30% vs 50% vs 100% guide.
Shijin Packaging — factory-direct cosmetic and daily-chemical plastic bottles since 2003, operating 30+ automatic blow-molding lines and 10+ injection-molding machines across a 15,000 m² facility in Huizhou, Guangdong, with daily capacity of approximately 200,000 pieces; recycled-content PCR bottles with per-batch chain-of-custody documentation.
- Website: https://shijinpackaging.com
- Full catalogue: https://shijinpackaging.com/catalog/
- Email: sales@shijinpackaging.com