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D2720-94 – Standard Test Method Technical Guide
The ASTM D2720-94 (Reapproved 2012) standard provides a comprehensive framework for calculating commercial weight and yield of scoured wool, top, and noil. This practice is essential for ensuring uniformity in trade and processing, considering various commercial compositions that include moisture, extractable materials, and mineral matter.
📊 Commercial Compositions and Designations
Commercial designations are predefined compositions used as standards for weight calculations. For instance, “Clean Wool Fiber Present” assumes specific percentages of components. Table 1 below lists typical compositions for several common designations used in the industry.
| 🟦 Commercial Designation | 📏 Moisture (%) | 📐 Extractable (%) | 🎯 Mineral Matter (%) | ⚡ Wool Base (%) |
|---|---|---|---|---|
| Clean Wool Fiber Present | 12.0 | 1.5 | 0.5 | 86.0 |
| American Dry Combed Top | 13.5 | 2.0 | 0.7 | 83.8 |
| Bradford Dry Combed Top | 14.0 | 1.8 | 0.6 | 83.6 |
| American Oil Combed Top | 12.5 | 2.5 | 0.5 | 84.5 |
The observed composition of a lot may vary from these standards. When it does, the weight is adjusted to the commercial weight using the proportions defined in Table 1. This adjustment ensures that all transactions are based on a consistent reference point.
⚖️ Commercial Weight and Yield Calculations
The calculation of commercial weight involves multiplying the observed weight by a factor derived from the commercial composition. For example, if the actual moisture content is higher than the commercial standard, the weight is reduced proportionally. The standard also provides methods for converting commercial weights between different designation bases, such as from “American Oil Combed Top” to “Bradford Dry Combed Top.”
Yield calculations from raw wool are similarly standardized. The yield on one commercial basis can be converted to another using the compositions in Table 1. This facilitates comparison across different processing stages and commercial agreements.
💡 Technical Note: All measurements should be performed following D584 for wool content. The term “weight” is retained per trade practice, though “mass” is the scientific term. Refer to Terminology D123 and D4845 for complete definitions.
⚠️ Safety Consideration: Users should assess all safety risks associated with sample preparation and chemical extractions. Appropriate personal protective equipment and handling procedures are recommended.
❓ Frequently Asked Questions
🔍 What is the role of commercial composition in wool trade?
Commercial composition establishes a uniform basis for weight and yield, allowing different parties to compare and transact wool products reliably.
💡 How is the commercial weight of a lot determined?
The commercial weight is calculated by adjusting the observed weight based on the differences between the actual composition and the commercial composition for the designated type.
⚡ Which ASTM standards are essential for this practice?
Essential standards include D123 (Terminology Relating to Textiles), D4845 (Terminology Relating to Wool), and D584 (Test Method for Wool Content of Raw Wool).
📌 What does “wool base” mean in calculations?
Wool base refers to the oven-dried weight of pure wool fiber, excluding all moisture, extractables, and mineral matter. It is the core component in commercial composition calculations.