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ISO 2061:2010 – Determination of Twist in Yarns by Direct Counting Method: Technical Overview and Compliance
A detailed guide for textile professionals on scope, technical requirements, implementation, and compliance of ISO 2061:2010 for yarn twist measurement.
ISO 2061:2010 is an internationally recognized standard that specifies the direct counting method for determining the twist in yarns, both single and folded. This method is essential for textile quality control, as twist directly influences yarn strength, appearance, handle, and processability. In many countries, including Canada, this standard is adopted as a national standard (e.g., CGSB 4.2 No. 31.1‑2010) to harmonize testing practices across industries.
1. Scope of ISO 2061:2010
The standard applies to single yarns and folded (ply) yarns made from staple fibres, filaments, or blends. It is not applicable to yarns with a linear density exceeding 2 000 tex (Nm 0.5) nor to yarns where the twist method would cause damage or alteration of the twist. The direct counting method is suitable for yarns where twist can be reliably counted by untwisting or by using a needle to separate fibres.
Yarn Types Covered
| Yarn Category | Typical Applications | Twist Range (turns/m) |
|---|---|---|
| Single staple yarn | Woven and knitted fabrics | 100–1 200 |
| Filament yarn | Technical textiles, apparel | 10–300 |
| Folded (ply) yarn | Sewing threads, denier fabrics | 100–800 |
2. Technical Requirements and Test Method
Principle
The principle involves clamping a known length of yarn under a specified tension and then untwisting the yarn until all fibres are parallel. The number of turns counted corresponds to the twist content in that length. For folded yarns, the twist in the final ply is measured after separating the plys.
Apparatus
- Twist tester (manual or automatic) with linear speed control.
- Clamps with defined gauge length (typically 100 mm, 250 mm, or 500 mm).
- Pretension device in accordance with ISO 2061 (tension based on linear density).
- Magnifying lens for fibre separation.
Key Parameters
| Parameter | Requirement | Remarks |
|---|---|---|
| Gauge length | 100 mm ± 1 mm | For yarns < 500 tex |
| Pretension | 0.5 cN/tex ± 0.1 cN/tex | Or as per product standard |
| Number of tests | At least 10 per sample | For statistical validity |
| Conditioning atmosphere | 20 °C ± 2 °C, 65% ± 4% RH | Standard textile testing conditions |
TIP: Ensure the twist tester is calibrated regularly using a reference yarn of known twist to maintain accuracy.
Calculation
Twist, T (in turns per metre) is calculated as:
T = (n × 1000) / L
where n = number of turns counted, L = test length in mm.
WARNING: For high‑twist or very fine yarns, careful fibre separation is critical to avoid miscounts. Use a needle and magnifier when needed.
3. Implementation Highlights
Successful implementation of ISO 2061:2010 requires attention to:
- Sample preparation: Yarn samples must be conditioned for at least 24 hours in the standard atmosphere. Yarn should be unwound from the package without tension to avoid twist loss.
- Test length selection: The standard allows different gauge lengths depending on twist level. Higher twist yarns may require shorter lengths to avoid breakage.
- Operator training: The direct counting method requires skilled operators to correctly identify twist direction (S or Z) and count turns accurately.
- Data recording: Record twist direction, number of tests, mean twist, and coefficient of variation.
GOOD PRACTICE: When testing folded yarns, first check twist of the single component, then measure the folding twist. The combined twist result helps evaluate yarn balance.
4. Compliance and Regulatory Notes
ISO 2061:2010 is widely accepted in international trade for verifying yarn specifications. National standards bodies, such as the Canadian General Standards Board (CGSB), have adopted this standard as CGSB 4.2 No. 31.1‑2010 with identical technical content. Compliance with ISO 2061 is often required in contracts between yarn suppliers and fabric manufacturers.
Accreditation and Quality Control
Testing laboratories seeking ISO 17025 accreditation should demonstrate competence in performing ISO 2061. Interlaboratory proficiency testing programs annually compare twist measurement results.
Common Non-Conformities
- Incorrect gauge length setting
- Inadequate conditioning time
- Failure to calibrate pretension device
- Mistaking twist direction (S/Z)
DANGER: Improper clamping can cause yarn slippage or breakage, leading to erroneous twist values. Always verify that the clamping pressure is adequate for the yarn type.
Frequently Asked Questions
Q: How does the direct counting method differ from the untwist/retwist method (ISO 2061 vs. ISO 17202)?
A: The direct counting method (ISO 2061) physically untwists the yarn and counts turns, while the untwist/retwist method (used for spun yarns) relies on extending the yarn after untwisting. Direct counting is suitable for most yarns; the untwist/retwist method is often used for staple fibre yarns where twist is difficult to count directly.
A: The direct counting method (ISO 2061) physically untwists the yarn and counts turns, while the untwist/retwist method (used for spun yarns) relies on extending the yarn after untwisting. Direct counting is suitable for most yarns; the untwist/retwist method is often used for staple fibre yarns where twist is difficult to count directly.
Q: What should I do if the yarn breaks during testing?
A: Discard the result and test a new specimen. Frequent breakage may indicate that the gauge length is too long or the pretension too high. Reduce gauge length or check if the yarn is damaged.
A: Discard the result and test a new specimen. Frequent breakage may indicate that the gauge length is too long or the pretension too high. Reduce gauge length or check if the yarn is damaged.
Q: Is ISO 2061:2010 applicable to textured yarns?
A: No. The direct counting method is designed for yarns with a uniform twist structure. For textured yarns, other standards (e.g., ISO 2062 for linear density) should be used.
A: No. The direct counting method is designed for yarns with a uniform twist structure. For textured yarns, other standards (e.g., ISO 2062 for linear density) should be used.