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D1907 – Standard Test Method Technical Guide
📋 Overview and Scope
ASTM D1907/D1907M-12 (2018) is a standard test method for determining the linear density of yarn (yarn number) using the skein method. It applies to all types of yarn in package form, with limitations on stretch and size as specified. The method provides for expressing yarn linear density in all traditional numbering systems.
This method is applicable to yarns that stretch less than 5% when tension is increased from 0.25 to 0.75 cN/tex [0.25 to 0.75 gf/tex]. For yarns that stretch more, lower reeling tension may be used by mutual agreement. Additionally, the method is suitable for yarns finer than 2000 tex, but can be adapted for coarser yarns with shorter skein lengths.
| 🟦 Parameter | 📏 SI Units | 📐 Inch-Pound Units |
|---|---|---|
| Minimum Tension | 0.25 cN/tex | 0.25 gf/tex |
| Maximum Tension | 0.75 cN/tex | 0.75 gf/tex |
| Maximum Stretch | 5% | 5% |
| Maximum Yarn Linear Density | 2000 tex | N/A |
📐 Moisture Content Options
The standard provides several options for determining the moisture content or condition of the yarn specimen, depending on whether the yarn is scoured or unscoured:
| 🎯 Option | ⚡ Description |
|---|---|
| Option 1 | Unscoured yarn at equilibrium with standard atmosphere |
| Option 2 | Oven-dried yarn |
| Option 3 | Oven-dried yarn plus commercial moisture regain |
| Option 4 | Scoured yarn at equilibrium with standard atmosphere |
| Option 5 | Oven-dried, scoured yarn |
| Option 6 | Oven-dried, scoured yarn plus commercial moisture regain |
| Option 7 | Oven-dried, scoured yarn plus commercial allowance (moisture regain + finish allowance) |
📊 Key Measured Properties and Applications
Linear density is the primary property measured, and it can be expressed in traditional yarn numbering systems. Specimens used in this test may also be used to determine skein breaking strength, providing efficiency in material testing. The method is recognized for use by U.S. Department of Defense agencies.
💡 Tip: For yarns coarser than 2000 tex, the method can be adapted by using shorter skein lengths and alternative reeling conditions, as agreed upon by the interested parties.
⚠️ Note: This standard does not purport to address all safety concerns. Users are responsible for establishing appropriate safety, health, and environmental practices.
❓ Frequently Asked Questions
🔍 What is the maximum stretch allowed for yarn in this test?
The yarn must stretch less than 5% when tension is increased from 0.25 to 0.75 cN/tex [0.25 to 0.75 gf/tex].
💡 Is this method applicable to glass or jute yarns?
Yes, but it is recommended to use other approved methods as specified in Specifications D541, D578/D578M, and D681 for these materials.
⚡ Can the linear density be determined from short-length specimens?
Yes, Test Method D1059 covers the determination of yarn number based on short-length specimens raveled from fabrics.
📌 What options are available for moisture content determination?
The standard offers seven options for different yarn conditions, including unscoured and scoured yarns, oven-dried, and with commercial allowances.