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D1575-13 – Standard Test Method Technical Guide
📐 Scope and Specimen Types
This test method covers the estimation of the average fiber length and length distribution of wool in nonparallel assemblies, such as scoured wool, and in card sliver. As outlined in Scope 1.1 and 1.3, it is not applicable to unscoured wool or to wool top. The values stated in inch-pound units are regarded as the standard, with metric units provided for information only (Scope 1.4). This method also references Terminology D123 and D4845 for definitions.
| 🟦 Specimen Type | 📏 Applicability | 📐 Notes |
|---|---|---|
| Scoured Wool | Yes | Nonparallel assembly |
| Card Sliver | Yes | Nonparallel assembly |
| Unscoured Wool | No | Grease wool; covered in Method D1234 |
| Wool Top | No | Parallel assembly; covered in Test Method D519 |
⚙️ Apparatus and Test Procedure
The apparatus includes a comb sorter similar to that described in Test Method D519, with modifications for fiber length. According to Note 2, for specimens with longest fibers not exceeding 6 in. (150 mm), one 15-in. (380 mm) sorter is used. For fibers exceeding 6 in., two sorters (8-in. or 15-in.) are required. The sample is prepared by hand carding when necessary, then manipulated on the comb sorter and separated into definite length increments. The weight of fibers in each length increment is obtained.
| 🎯 Maximum Fiber Length | ⚡ Sorter Configuration |
|---|---|
| ≤ 6 in. (150 mm) | One 15-in. (380 mm) sorter |
| > 6 in. (150 mm) | Two sorters: 8-in. (200 mm) or 15-in. |
📊 Key Measured Properties and Calculations
From the weight data, estimates of the weight-biased average fiber length and weight-biased length distribution are calculated (Summary 4.1). This method is useful for in-plant control testing and research purposes (Significance 5.2). However, due to poor between-laboratory precision, it is not recommended for acceptance testing (Significance 5.1). In case of disputes, a comparative bias study between laboratories is suggested.
⚠️ Precision Warning: This test method is not recommended for acceptance testing due to its poor between-laboratory precision. For commercial shipments, statistical bias between laboratories should be determined if this method is used.
💡 Unit Information: The standard specifies inch-pound units as the standard. Metric units in parentheses are provided for information only, in compliance with ASTM policy.
❓ Frequently Asked Questions
🔍 What is the purpose of this test method?
This test method covers the estimation of the average fiber length and length distribution of wool in nonparallel assemblies, such as scoured wool and card sliver, using a comb sorter and weight measurements.
💡 Is this method applicable to wool top?
No, this test method is not applicable to wool top or unscoured wool. Wool top is covered in Test Method D519, and grease wool staple length is covered in Method D1234.
⚡ What apparatus is required for this test?
The apparatus is a comb sorter, similar to that in Test Method D519, with modifications. The configuration depends on fiber length: one 15-in. sorter for fibers up to 6 in., and two sorters for longer fibers.
📌 Why is this method not recommended for acceptance testing?
Due to its poor between-laboratory precision, this method is not recommended for acceptance testing. For commercial shipments, alternative methods or comparative bias studies may be necessary.