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D2258 – Standard Test Method Technical Guide
📦 Scope and Applicable Materials
ASTM D2258/D2258M‑16 (Reapproved 2022) establishes a uniform procedure for dividing yarn shipments into test lots and selecting representative samples for testing. Under the jurisdiction of ASTM Committee D13 on Textiles, this practice applies to single, plied, and cabled yarns, as well as cords, manufactured from any fiber or mixture of fibers. Section 1.2 confirms that the standard supports all common package forms, including cones, cases, and beams.
The scope extends to both pre‑fabric production lot testing and post‑fabric sampling. Section 1.3 provides a critical caveat: yarns removed from woven or knitted fabrics are rarely representative of entire shipments and are typically unsuitable for acceptance testing, although they may be used for yarn characterization. Section 1.4 also emphasizes that SI and inch‑pound units must be treated as independent systems and never combined for conformance.
| 🧵 Yarn & Material Type | 📦 Supported Package Forms | 🎯 Primary Testing Applicability |
|---|---|---|
| Single, Plied, or Cabled Yarns | Cone, Case, Spool, Beam Set | Pre‑fabric & Post‑fabric Lot Acceptance |
| Cords & Twines | Beam, Reel, Large Package | Process Control & Shipment Verification |
| Yarns from Woven / Knitted Fabric | Fabric Package (Swatch, Roll) | Yarn Characterization Only (Not Acceptance) |
📐 Sampling Plan and Key Terminology
Section 4.1 of the practice details the sampling framework. Users must first divide the consignment into distinct lots, then determine the number of cases, beams, or fabric packages to select as the lot sample. From this lot sample, a laboratory sample is drawn, consisting of specific packages (including the number of ends) that will be subjected to physical testing. The procedure ensures that the specimen set reflects the variability of the entire shipment.
⚠️ Important Caveat for Fabric‑Sourced Samples
Per Section 1.3, when yarns are removed from woven or knitted fabrics, the sampling can only be used to determine yarn characteristics and is usually not appropriate for acceptance testing. Be aware that properties of yarns from fabric may differ from the same yarn prior to fabric manufacturing.
Per Section 1.3, when yarns are removed from woven or knitted fabrics, the sampling can only be used to determine yarn characteristics and is usually not appropriate for acceptance testing. Be aware that properties of yarns from fabric may differ from the same yarn prior to fabric manufacturing.
| 📘 Term (Section 3.2) | ⚙️ Definition in Sampling Context |
|---|---|
| Lot Sample | The collection of primary sampling units selected from the production lot or shipment for evaluation. |
| Laboratory Sample | The packages, ends, or sample skeins taken from the lot sample for laboratory testing. |
| Primary Sampling Unit | The initial unit drawn from the lot (e.g., shipping case, beam, fabric package). |
⚙️ Significance and Use for Lot Testing
Assigning a value to any yarn property involves a combined measurement process of sampling and testing. Section 5.1 highlights that the correctness of the assigned value depends directly on the variability contributed by both the testing equipment and the sampling plan. Using this practice ensures that the sample structure is statistically appropriate for the material and the specific test method employed (e.g., D1578 for breaking strength or D1907 for linear density).
💡 Dual Unit System Best Practice
Section 1.4 specifies that values stated in SI units or inch‑pound units shall be regarded separately as standard. To ensure conformance, always select one unit system and use it consistently throughout your entire sampling and testing program. Never combine values from the two systems.
Section 1.4 specifies that values stated in SI units or inch‑pound units shall be regarded separately as standard. To ensure conformance, always select one unit system and use it consistently throughout your entire sampling and testing program. Never combine values from the two systems.
Proper application of D2258 requires familiarity with Terminology D4849 (Yarns and Fibers) and D123 (Textile Terminology). The sampling plans defined here form the backbone of reliable lot acceptance testing, helping laboratories and manufacturers minimize risk by controlling sampling variability.
❓ Frequently Asked Questions
🔍 What does the dual designation D2258/D2258M signify?
The “M” indicates a metric (SI) version of the standard. The double designation allows the same sampling practice to be used with both SI and inch‑pound units, but each system must be used independently per Section 1.4.
💡 Is D2258 valid for sampling yarns from knitted fabric?
Yes, Section 1.3 explicitly covers yarns removed from woven or knitted fabrics. However, these samples are generally not representative of entire shipments and should not be used for acceptance testing without recognizing the limitations described in the standard.
⚡ What is the difference between a lot sample and a laboratory sample?
Per Section 4.1, the lot sample is the collection of primary units (e.g., cases or beams) drawn from the lot. The laboratory sample is the specific packages or ends taken from the lot sample that will be used for the actual laboratory determination.
📌 Which ASTM terminology standards support this practice?
Terminology for yarns and fibers is defined in D4849. General textile terms are given in D123. Specific test methods like D1578 (Skein Breaking Strength) and D1907 (Yarn Linear Density) are also referenced for the testing phase of the sampling process.