Direct Answer
Mass balance certification is the accounting method that lets a supplier claim recycled content in packaging even though recycled and virgin material are physically blended during production. The system tracks the recycled input, then allocates a share of it to specific outputs, and the claim is valid at the system level when a recognised scheme verifies it. The buying risk is in how the claim is worded: a mass balance claim can be applied to a unit that contains little recycled material in that specific piece, so it must be read together with the allocation method. Ask for the scheme, the certificate number, and the allocation model, then confirm the certificate covers the actual material and plant that supply you.
Opening Hook
A food brand bought a "30% recycled content" tray, quoted the number on its pack, and later found the claim covered a mass balance allocation across the supplier's entire plant, not the specific tray in the box. A customer question turned into a compliance headache because the wording had not named the allocation method. The recycled material existed somewhere in the system; the claim just did not say how it was allocated. At ecosora, we read recycled content claims together with their certification method, because a percentage without a scheme and an allocation model is a number, not a verified claim.
Mass Balance vs Segregated Accounting
Understand the two allocation models before you buy.
| Model | How It Works | Claim It Supports |
|---|---|---|
| Segregated | Recycled material kept separate end to end | "This unit contains X% recycled" |
| Mass balance | Recycled input mixed, then allocated | "X% of input credited at system level" |
| Controlled blending | Partial segregation with documentation | A middle-ground claim |
| Book-and-claim | Credits decoupled from physical flow | Credit transfer, not content |
The table matters because the same "30% recycled" number means different things under different models. A segregated claim describes the physical unit; a mass balance claim describes the system, and the buyer must know which one they are reading. Match the claim wording to the model, and do not let a system-level number be presented as a unit-level fact.
Data: ISO's standards catalogue covers the chain-of-custody and recycled content standards that mass balance and segregated certification schemes draw on, providing the accounting basis for verified claims.
Judgment: Require the named certification scheme and allocation model behind any recycled content claim, because a percentage without a scheme cannot be audited or defended.
Source: ISO — ISO Standards Catalogue (2024)
What to Ask the Supplier
| Question | Why It Matters |
|---|---|
| Which scheme issued the certificate? | Determines audit credibility |
| What is the certificate number? | Lets you check validity |
| Which allocation model applies? | Segregated vs mass balance |
| Which plant and grade are covered? | Certificate must match supply |
| Can I see the chain-of-custody audit? | Confirms ongoing verification |
The questions convert a marketing claim into a verifiable file. A supplier who can answer all five has a real certification program; one who answers "we're certified" without details is offering an assertion. Hold the certificate with the specification, and re-check it when the recycled content packaging guide adds a new grade to the range.
Claim Wording That Holds Up
| Wording | What It Implies | Risk |
|---|---|---|
| "Made with 30% recycled content" | Unit-level physical content | High if mass balance |
| "30% recycled content, mass balance" | System-level allocation | Low, transparent |
| "Contains recycled material" | Unquantified | Vague but safe |
| "100% recycled" | Full recycled input | Requires proof |
The safest wording names the model next to the number, so the reader can see how the claim was produced. A unit-level phrase attached to a mass balance allocation is where most recycled content claims fail a review, because the physical unit and the credited system are different things. Keep the wording inside what the certificate actually supports.
Data: The European Commission's packaging policy framework promotes recycled content targets in packaging and references the verification approaches that make such claims credible on the EU market.
Judgment: Treat recycled content targets as a reason to demand verified chain-of-custody documentation, not as permission to claim content on the basis of supplier statements alone.
Source: European Commission — Packaging and Plastics Policy (2024)
Verifying the Certificate
| Check | What to Confirm |
|---|---|
| Scheme validity | Certificate is current, not expired |
| Scope match | Covers the grade and plant supplying you |
| Allocation model | Matches the claim wording you use |
| Auditor | Scheme is independently audited |
| Renewal | Chain of custody is ongoing |
A certificate is a point-in-time document, so confirm it is current and covers what you actually buy. A valid certificate for one grade does not transfer to a different material, and a mass balance certificate does not license a segregated claim. Where recycled content feeds a carbon footprint measurement program, the allocation model also affects how the recycled input is counted, so keep the two files aligned.
Common Certification Mistakes
| Mistake | Consequence | Prevention |
|---|---|---|
| Unit-level wording on mass balance | Misleading claim | Name the model in the wording |
| Expired certificate cited | Unsupported claim | Check currency at every order |
| Wrong grade cited | Claim does not transfer | Match certificate to SKU |
| No scheme named | Unverifiable number | Require scheme and certificate |
| Segregated implied, mass balance used | Audit finding | State the actual model |
Each mistake is a gap between what the claim says and what the certificate proves. Closing the gap is mostly a documentation discipline: name the scheme, name the model, and keep the certificate with the specification, then the recycled content claim survives both a customer question and a regulator's review.
Data: The Biodegradable Products Institute (BPI) runs a North American certification program for compostable products, illustrating how third-party verification turns a material claim into a checkable credential.
Judgment: Extend the same third-party verification logic to recycled content — an unverified percentage is a marketing statement, while a certified one is a specification item.
Source: Biodegradable Products Institute (BPI) — Compostability Certification (2024)
The Bottom Line
Recycled content mass balance certification is credible only when the scheme, the certificate number, and the allocation model are named next to the claim, and the wording stays inside what the certificate proves. In one sentence: ecosora reads recycled content claims with their certification method, so a percentage never outruns the document behind it.