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D3939 – Standard Test Method Technical Guide
📐 Scope and Applicability
The ASTM D3939/D3939M −13 (Reapproved 2017) standard is specifically designed to determine the snagging resistance of fabrics using the Mace test method. According to Section 1.1, its primary function is the evaluation of a fabric’s ability to resist snagging. The standard is applicable to a wide range of woven and knitted fabrics made from textured or untextured filament yarns, spun yarns, or any combination of these yarn types.
However, the standard explicitly defines its limitations in Section 1.2. It is strictly not suitable for open construction fabrics like nets, as the mace points will snag the underlying felt pad rather than the specimen itself. Similarly, very heavy or stiff fabrics that cannot conform tightly to the drum and felt pad are excluded, along with all tufted and nonwoven fabrics, as the apparatus is engineered specifically for woven and knitted structures.
| 🟦 Key Terminology Defined (Section 3.1) | 📐 Context of Definition |
|---|---|
| Color Contrast | In textiles, a visual criterion for assessing the severity of snagging. |
| Distortion | In fabrics, a measure of yarn displacement caused by the mace. |
| Protrusion | In textile surfaces, describing the physical lifting of yarn. |
⚙️ Referenced Standards and Test Condition Framework
The execution of D3939 is highly dependent on a suite of complementary standards. Section 2 lists the critical ASTM and AATCC standards that support this test method. For instance, Practice D1776 governs the conditioning and testing atmosphere for all specimens. The standard also points to D5362 as an alternative snagging test methodology. Furthermore, the terminology foundation is built upon D123, D4850, and D3136, providing precise definitions for related textile properties.
Safety is also addressed within this framework. Section 1.5 reminds users that the standard does not cover all safety concerns and mandates that the user establishes appropriate safety and health practices. Specific precautionary statements are detailed in Section 7 of the standard.
| 🟦 Referenced Document | 🎯 Role in Test Method |
|---|---|
| ASTM D1776 | Standard practice for conditioning and testing textiles. |
| ASTM D5362 | Alternate method for snagging resistance (Bean Bag method). |
| AATCC 135 | Standard for dimensional changes in automatic home laundering. |
| ASTM D2724 | Test methods for bonded, fused, and laminated apparel fabrics. |
⚠️ Critical Note on Unit Systems: As per Section 1.4, the values stated in SI units and other units are not exact equivalents and must be kept strictly separate. In all arbitration or referee decision scenarios, the SI units are the definitive standard.
📊 Limitations and Alternative Test Methods