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D6466-10 – Standard Test Method Technical Guide
📐 Scope and Applicability
This test method, designated D6466 −10 (Reapproved 2018), establishes a procedure for the determination of the average fiber diameter and the fiber diameter variation in wool and other animal fibers using the Sirolan-Laserscan Fibre Diameter Analyser. The method covers fibers in their various forms, including raw wool, top, and yarn.
The standard specifies that values shall be regarded as standard in SI units (μm). As stated in Section 1.3, users are responsible for establishing safety, health, and environmental practices in compliance with applicable regulations. This international standard was developed in accordance with the World Trade Organization principles on standardization.
⚙️ Test Procedure and Sample Preparation
The test method involves a systematic sampling protocol. Raw wool requires core sampling per Practice D1060 and cleaning per Test Method D584. All textile samples must be conditioned according to Practice D1776. The bulk sample is reduced to small snippets of fiber, which are then dispersed in a liquid medium.
The suspension of snippets is passed through the optical cell of the Sirolan-Laserscan. A laser beam scans the stream, measuring the diameter of each fiber snippet. The instrument automatically calculates the mean fiber diameter, standard deviation, and coefficient of variation. The procedure aligns closely with IWTO-12, which is the international method for this specific instrument referenced in Section 2.2 of the standard.
⚠️ Safety Note (Section 1.3): This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user to consult and establish appropriate safety, health, and environmental practices before using the equipment and preparing fiber snippets.
📊 Key Measured Properties and Reference Data
The primary output of the test method is the Mean Fiber Diameter (MFD) and the Coefficient of Variation of Diameter (CVD%). These results are critical for grading the fiber according to specifications such as D3991 (fineness of wool or mohair) and D3992 (wool top or mohair top). The test method relies heavily on a network of related ASTM, federal, and international standards.
| 🟦 Standard / Regulation | 📏 Subject Matter |
|---|---|
| D2130 | Test Method for Diameter of Wool and Other Animal Fibers by Microprojection |
| D3991 / D3992 | Specifications for Fineness of Wool/Mohair and Assignment of Grade |
| D2816 | Test Method for Cashmere Coarse-Hair Content in Cashmere |
| IWTO-12 | Measurement of the Mean and Distribution of Fibre Diameter Using the Sirolan-Laserscan |
| U.S. Federal (31.04, 31.204) | Official Standards of the United States for Grades of Wool |
| 🎯 Fiber Form | 📐 Preparation Notes |
|---|---|
| Raw Wool | Core sampling per D1060; cleaning per D584. |
| Wool / Mohair Top | Direct snipping; grading per D3992. |
| Cashmere | Test for coarse-hair content per D2816. |
| Alpaca | Fineness specification per D2252 (historical). |
💡 Method Advantage: The Sirolan-Laserscan provides a fully automated and rapid measurement of fiber diameter, significantly increasing throughput and reducing operator variability compared to the traditional projection microscope method (D2130). It is the industry standard for high-volume wool testing and grade assignment.
❓ Frequently Asked Questions
🔍 What types of animal fibers can be tested?
As per Section 1.1, the method covers wool and other animal fibers, including cashmere, mohair, alpaca, and similar specialty fibers. The standard provides specific references for fineness and coarse-hair content for these fibers (e.g., D2816 for cashmere).
💡 What is the difference between D6466 and IWTO-12?
While the instrument and core procedure are the same, D6466 is the ASTM standard that tailors the Laserscan method for regulatory compliance in the U.S. It explicitly references ASTM practices for sampling (D1060, D584), conditioning (D1776), and grading (D3991, D3992), alongside the U.S. Federal Standards for wool grades referenced in Section 2.2.
⚡ What units is the fiber diameter reported in?
The fiber diameter is reported in micrometers (µm), as SI units are regarded as the standard per Section 1.2.
📌 What is a “snippet” (Section 3.1.1)?
A snippet is a small, precisely cut segment of fiber, typically 1 to 2 mm in length. The bulk sample must be reduced to these snippets so fibers can be individually suspended in a liquid medium and accurately measured by the laser beam of the Sirolan-Laserscan analyser.