Surface Performance / Pulled Loops / Mace Test
How Is Snagging Resistance Tested in Knitted Fabric?
Snagging begins when a projecting point catches yarn at the fabric surface. A controlled mace test reproduces repeated catching actions; the result is a visual record of loops, protrusions, and distortion, not a prediction that a garment can never snag.
Snagging resistance is tested by conditioning representative fabric specimens, mounting them according to a named method, and exposing their faces to repeated contact with a mace, or spiked ball, in controlled apparatus. The action catches and draws surface yarns in a repeatable way. After the prescribed exposure, specimens are assessed for pulled loops, protrusions, distortion, and overall appearance under defined viewing conditions. A useful result identifies the standard and edition, fabric face and direction, specimen state, pretreatment, exposure, assessment system, individual ratings, and acceptance rule.
Snagging is a local yarn displacement, not general surface wear
A snag forms when a projecting or rough object engages a yarn segment and pulls it away from the fabric plane. In a knitted structure, that local movement can draw yarn from adjacent loops, tighten neighbouring stitches, create a visible line, or leave a loop above the surface. The yarn may remain intact even though the appearance has changed materially. If a filament or yarn breaks, the event can progress into a hole, run, or ladder, but breakage is not required for a defect to be classified as a snag.
Snagging should not be used as another name for pilling. Pilling develops when protruding fibres entangle into small balls that remain attached to the surface. Nor is snagging identical to abrasion, which concerns progressive surface change under rubbing. A fabric can resist abrasion yet form a conspicuous pulled loop after contact with jewellery, a rough table edge, hook-and-loop fastening, or a sharp component on a bag. Separate mechanisms require separate tests.
ISO 25086-1:2026 specifies a mace test for determining the snagging resistance of knitted and woven fabrics. ASTM D3939/D3939M-26 also addresses mace snagging across a range of knitted and woven fabrics made from spun yarns, filament yarns, or combinations. The method name matters because apparatus, specimen preparation, exposure, and rating conventions are part of the result. A grade from one procedure should not be silently compared with a count from another.
A snag rating is visual evidence
The number of pulled loops is only one part of appearance. Length, contrast, local puckering, a drawn line, and the position of the snag can make two specimens with a similar count look very different.
A mace test controls contact, specimen state, and assessment
Testing begins with representative sampling. Specimens should preserve the orientation of the courses and wales and should not all be cut from the same narrow path through a fabric length. For engineered panels, plain ground, cable field, transferred area, intarsia boundary, pocket, and trim may have different exposures and should be treated as different constructions when the risk justifies it. The face intended for wear is identified before cutting.
Conditioning is essential because moisture, recent steaming, laundering, and finishing can alter loop dimensions, yarn friction, surface hair, and fabric stiffness. ISO 139 defines standard atmospheres for conditioning and textile testing. A specimen tested directly from finishing is not automatically comparable with one that has been washed, dried, pressed, or allowed to relax. ASTM D3939 notes that snagging can be affected by laundering or drycleaning and that testing before and after the intended care route may be advisable.
In a mace procedure, specimens are fitted to the prescribed supports and subjected to repeated, method-defined contact from a spiked mace while the apparatus operates. The geometry is designed to produce catching events under controlled conditions rather than reproduce one specific accident. Mounting tension, seam placement on the holder, felt condition, apparatus state, exposure duration, and specimen alignment must follow the selected standard. A loose mount or worn test component changes the severity of the action.
After exposure, specimens are removed without smoothing away the evidence. They are allowed to recover where the method requires it, then viewed under controlled lighting and orientation. Depending on the procedure and agreed specification, assessment may use visual standards, snag counts, categories of defect, or a combined appearance judgement. ASTM D3939 cautions that visual acceptability depends on more than the number of snags: colour contrast, long distortions, and long protrusions can materially change perception. Individual observations and variability should therefore remain in the report rather than being reduced to an unsupported single adjective.
Method suitability must also be checked. ASTM D3939 excludes open net constructions where mace points can engage the underlying felt instead of the specimen, very heavy or stiff fabrics that cannot fit the drum correctly, and tufted or nonwoven structures. It also notes that another method may be needed for a different fabric or end use. Choosing a gentler or more severe test after seeing an inconvenient result is not valid; the procedure should be selected and documented before approval testing begins.
Loop exposure and yarn mobility shape the result
Construction determines where a catching point can enter. Long floats, elongated stitches, openwork, tuck accumulation, transferred eyelets, brushed surfaces, bouclé effects, loose ends, and raised relief present different engagement opportunities from a compact plain structure. A long float can be drawn outward; an open loop can receive the point; a cable crossing can create height and local mobility. Increasing cover or shortening an exposed yarn path may reduce risk, but it can also alter hand, drape, weight, transparency, and the intended visual scale.
Stitch length affects loop size and the amount of yarn available to redistribute around a pull. Course and wale density affect cover and restraint. Transfers, miss stitches, and changes between single- and double-bed structures introduce zones with different yarn paths. A shaped garment should therefore be reviewed as a map of constructions, not represented automatically by one plain swatch.
Yarn construction also matters, but fibre name alone does not predict snagging. Twist, ply, filament count, texturing, hairiness, cohesion, bending stiffness, friction, and finish influence whether a catching point slides away, raises a filament, or draws a complete yarn segment. Yarn twist can change surface cohesion and handle at the same time. A finish may temporarily suppress surface mobility, while laundering may remove that effect or change the fabric geometry.
Colour and light reflection change the visibility of the same physical event. A pale pulled loop against a dark ground, a lustrous filament turned out of plane, or a long distortion crossing a regular stripe may be more noticeable than several short pulls in a mottled surface. This is why an appearance review should accompany the numerical result and why approval on one colourway does not automatically clear every colour combination.
Development should connect the test to the intended garment
A snagging specification should begin with exposure: outerwear, an open evening knit, an underlayer, a bag surface, and upholstery do not meet the same objects in use. High-contact zones such as cuffs, side seams, elbows, pocket openings, shoulders under straps, and trims may require targeted review. Laboratory specimens provide controlled comparison, but ASTM D3939 notes that wearer behaviour and conditions of use create wider variation in garments than among replicate test pieces.
For development, retain the approved method and edition, sampling plan, fabric face, course and wale orientation, pretreatment and care state, conditioning, number of specimens, apparatus exposure, rating procedure, visual standard, target, tolerance, and decision rule. If two laboratories produce materially different results, ASTM recommends comparative testing on homogeneous material and statistical review rather than assuming one result is correct. That limitation is particularly important when a grade is used for shipment acceptance.
The most useful response to a poor result is diagnostic. Record whether the defect is a short loop, long protrusion, line distortion, local tightening, filament break, or developing hole. Compare constructions while holding yarn and finish stable, then compare yarn or finish while holding the knit structure stable. Review the intended care cycle and garment hardware. During technical development, this evidence can be translated into stitch architecture, yarn specification, finishing, panel placement, and quality-control instructions rather than an indiscriminate request to make the fabric tighter.
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Common questions about snagging resistance
Why do knitted fabrics snag?
Knits contain intermeshed loops and, in many designs, floats or raised elements that can be engaged by a projecting point. When the point moves, yarn can redistribute from adjacent stitches and form a pulled loop or distortion without necessarily breaking.
Is snagging the same as pilling?
No. A snag is displaced yarn or a pulled loop caused by catching. A pill is a ball of entangled fibres formed through surface fuzzing and friction. The defects can coexist, but their mechanisms and test methods differ.
Does a high abrasion result mean good snag resistance?
No. Abrasion applies repeated rubbing; snagging applies a catching action. A compact surface may withstand rubbing yet contain an exposed float that is easily pulled by a point.
Can open lace be tested with a mace method?
Not always. ASTM D3939 identifies open net constructions as unsuitable when the mace can catch the felt beneath the specimen. The laboratory should confirm method applicability before setting a target.
Should snagging be tested after washing?
When the product will be laundered or drycleaned, comparison before and after the intended care route can be useful. Care can alter loop geometry, stiffness, hairiness, and finishes that influence surface mobility.
What is a good snagging grade for knitwear?
There is no universal grade for every knitted product. The appropriate criterion depends on method, end use, construction, colour contrast, exposure, visual standard, and buyer specification. The method and acceptance rule must travel with the result.
Snagging resistance is a controlled comparison of surface vulnerability
The test does not promise immunity from sharp objects. It reveals how a specified fabric state responds to a defined catching action. When the visual evidence is read alongside loop architecture, yarn construction, finishing, colourway, care, and garment placement, it becomes a practical development tool rather than an isolated grade.