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D5663-15 – Standard Test Method Technical Guide
🧮 Mass Balance Calculation Methodology
ASTM D5663‑15 (Reapproved 2020) establishes a mass balance approach as the sole recommended method for validating recycled content in packaging paper and paperboard. Since no physical or chemical test method can determine the absolute recycled fiber content of a finished product, the guide mandates that calculations be based on time weighted average flows derived from furnish component flow rates and consistency.
The methodology may be applied by batch or as a time weighted average for a specific grade or group of similar grades. The time frame for the calculation must be strictly constrained by the paper machine and the specific grade being produced (see Sections 10.1.1.1 and 10.1.1.2). Results are recorded in pounds per ton (lb/ton) or kilograms per tonne (kg/tonne).
A critical prohibition within the standard is against mathematical apportionment. If a manufacturer uses a 50% time-weighted average of recycled fiber over the defined period, the product must be reported as having 50% recycled content. It cannot claim that 50% of the production volume is 100% recycled.
📊 Data Requirements and Substantiation
Substantiation requires rigorous tracking of the fiber furnish. The data must include the type of fibers (virgin versus recycled), the volume of flow for each stream, and the time period considered. Pulping and recycling yields are explicitly excluded from the calculation. The recycled fiber content in the finished product is purely a function of the fiber types in the furnish flows, the volume of flow, and the selected time period.
| 🟦 Parameter | 📐 Specification from D5663 |
|---|---|
| Underlying Principle | Mass balance based on furnish flows |
| Calculation Units | lb/ton or kg/tonne |
| Time Frame | Constrained by machine and grade (Section 10) |
| Calculation Basis | Furnish component flow rates & consistency |
| 🚫 Prohibited Method | Mathematical apportionment of fiber content |
| ⚡ Excluded Factors | Pulping and recycling yields |
⚠️ Scope and Key Limitations
The guide covers all packaging paper and paperboard containing any amount or kind of recycled fiber. It can also be used, with appropriate modifications, to calculate the recycled content of recovered non‑fibrous materials such as fillers. However, the standard does not prescribe a specific amount or type of recycled content—that decision is strictly a matter of agreement between the buyer and the seller.
⚠️ No Direct Test Available: As explicitly stated in the scope, no physical or chemical test method exists to determine absolute recycled content in a finished product. Validation strictly requires the implementation of a robust mass balance tracking system.
🚫 Prohibition of Mathematical Apportionment: Using a 50% average of recycled fiber does not allow a manufacturer to claim 50% of production is 100% recycled. The entire production run must reflect the time‑weighted average percentage.
| 📌 Scope Element | 🟦 Specification |
|---|---|
| Recycled Fiber Content | Any amount or kind is covered |
| Nonfibrous Recycled Materials | Covered with appropriate modifications |
| Recommended Content Level | Not specified; agreed upon by buyer/seller |
| Consumer‑Facing Claims | May/may not comply with laws; see Appendix X1 |
❓ Frequently Asked Questions
🔍 How is recycled content validated if no physical test exists?
The D5663 standard mandates a mass balance approach. Manufacturers must calculate the time-weighted average of recycled fiber in their furnish flows over a constrained timeframe. This is the sole recognized method for validation.
💡 Can a company claim 50% of its output is 100% recycled if it uses 50% recycled fiber?
No. The standard explicitly prohibits this mathematical apportionment. The average recycled fiber content applies to the entire production volume for that grade and time period.
⚡ Are pulping and recycling yields considered in the calculation?
No. Section 1.1.2 clearly states that pulping and recycling yields are not used in the calculations. The recycled content is solely a function of the furnish flow rates, fiber types, and the time period.
📌 Who determines the appropriate recycled content level?
The standard does not recommend a specific amount or kind. The target content level and any claims made are strictly a matter of agreement between the buyer and the seller, as stated in Section 1.3.