How Is Wicking Measured in Knitted Fabric?

Wicking is measured by placing a controlled liquid in contact with a conditioned specimen and recording how far, how fast, or across what area the liquid moves. A vertical method may time the rise to specified distances or measure distance at fixed intervals. A horizontal method follows the wetted area over time. Image-based methods can quantify movement through and across the fabric in more than one direction. The report must name the method, liquid, dose or immersion depth, specimen face and orientation, time points, units, conditioning and care state, and replicate results.

Wicking is transport, not a general moisture claim

Wicking occurs when wetting and capillary pressure draw liquid along connected spaces within yarns, between fibres or filaments, and through the geometry of the fabric. In knitted material, those pathways are formed by loop heads, legs, sinker arcs, inter-yarn contacts, surface fibres, and any open or compact zones created by the stitch programme. Gravity opposes vertical rise and plays a different role in a horizontal spread test, which is why orientation is part of the result.

Wicking is not the same as absorbency. Absorbency concerns how much liquid a material takes up or retains under defined conditions; wicking concerns movement. A fabric can transport a small dose rapidly while holding relatively little inside the fibre, or absorb a large quantity without distributing it quickly. Wicking is also distinct from air permeability, water-vapour resistance, and drying rate. They may interact in use, but each needs its own measurement.

AATCC TM197 evaluates vertical wicking rate to specified distances. AATCC TM213 observes the distance reached after the cut edge is immersed and reports short- and longer-interval rates, including observations at 120 and 600 seconds. AATCC TM198 measures horizontal transport as wetted area per unit time. AATCC TM217-2025 adds an image-analysis approach that measures and classifies moisture movement vertically and horizontally, through and across textile samples. These procedures are not four labels for an identical number.

The method should follow the development question

For vertical testing, a strip is aligned so its lower edge contacts or enters the specified liquid. Capillary action draws the liquid upward against gravity. Under TM197, the laboratory records the time required to reach defined distances. Under TM213, the visually observed liquid front is recorded at defined intervals and converted to a rate. The specimen must hang without twist or unintended contact, and the immersion depth, marked distances, time origin, and observation technique must remain consistent.

Horizontal testing places the specimen flat and introduces liquid in the prescribed manner. TM198 follows the area of the spreading front at selected time intervals, so the result is expressed as area per time rather than a vertical distance. A horizontal procedure can expose asymmetric spreading along courses and wales, but a single circular area assumption can hide that anisotropy unless the method or imaging records it.

TM217-2025 is part of the 2026 AATCC Manual and uses imaging and data analysis to measure, evaluate, and classify movement vertically and horizontally. Its scope covers textile fabrics that transport moisture and excludes loose yarns and fibres; narrow and nonwoven materials may require modification. Image analysis can reveal through-plane and in-plane behaviour that a ruler observation cannot, but lighting, dosing, specimen presentation, thresholding, and the named calculation remain controlled parts of the procedure.

Sampling and conditioning come first in every case. The specimen should represent the construction zone, colourway, finish, and approved state. ISO 139 defines standard atmospheres for textile conditioning and testing. If a knit combines plain ground, mesh, rib, tuck, transfer, plating, or integral trim, those areas may require separate measurements rather than one average. Both fabric faces should be considered when yarn placement or finish is asymmetric.

Capillary continuity begins with fibre and ends with the finished loop

Fibre surface energy affects whether the liquid wets the material and enters a capillary pathway. Fibre chemistry alone, however, cannot predict a fabric result. Filament cross-section, texturing, staple length, hairiness, yarn twist, ply, compactness, and processing auxiliaries determine the size and continuity of channels. Yarn count and twist can open one route while closing another.

Loop geometry adds a second scale. Stitch length, machine gauge, take-down, course density, wale density, and relaxation govern contact between neighbouring loops. Tuck stitches accumulate yarn and can redirect liquid; floats can create lengthwise pathways; transferred eyelets interrupt the ground while exposing edges; ribs introduce two-bed geometry; plated constructions place different yarn systems on opposite faces. A value from the face yarn cannot be assumed to describe transfer through the complete structure.

Finish is often decisive. Hydrophilic treatments can improve initial wetting and spreading, while oils, softeners, resins, coatings, or contamination can suppress or localize it. Dye and finish recipes may vary by colour. Washing can remove a temporary auxiliary, activate or exhaust a finish, relax the loops, and change thickness. For this reason AATCC TM213 notes the influence of fibre content, construction, and mechanical or chemical processing; none should be removed from the interpretation.

Cut edges also matter. A vertical strip exposes severed yarn ends that may take up liquid differently from an intact garment surface. Edge fraying, curling, and distortion can alter contact with the bath. The laboratory should follow the method's preparation and report deviations. A development team should not translate a strip result into a garment claim without considering seams, ribs, hems, facings, layered areas, and the actual orientation of the knitted panels.

Comparable evidence requires a controlled specimen map

The intended function determines the useful comparison. A next-to-skin panel may need liquid to leave the inner face and spread on the outer face. A compact luxury layer may prioritize stable handle and appearance over maximal spread. An engineered garment may use a dense support zone beside an open transport zone. “Higher wicking” is not automatically the correct objective; the route, direction, amount, and destination of liquid have to match the garment system.

During sampling, change one variable group at a time. Compare course and wale directions on the same finished panel. Compare faces where plating or finishing is asymmetric. Hold yarn and dye route constant when evaluating stitch architecture; hold structure constant when evaluating yarn or finish. Test the initial and approved cared states when performance must survive laundering. Record individual traces or observations, not only the mean, because irregular spread can reveal a finish or construction problem hidden by an average.

A production-facing report should identify the standard and edition, liquid composition and temperature, dosing or immersion procedure, specimen dimensions, face, course and wale orientation, atmosphere, pretreatment, care cycle, observation intervals, endpoint, calculation, units, number of specimens, individual values, mean, and relevant variability. Photographs or spread maps can support the numerical record when appearance or direction is material.

The development process converts these observations into yarn selection, stitch mapping, face placement, finishing controls, and factory handoff. Structural examples are collected in Work. Anne's role is set out in About; specific development questions can be submitted through the contact form.

Common questions about wicking

Wicking becomes useful when route and direction stay visible

A wicking value should describe how liquid moved through a named construction under a named procedure. When face, direction, liquid, time, finish, and care state remain attached, it becomes actionable development evidence. When they disappear, a broad moisture claim replaces the measured behaviour.

Wicking and surface repellency describe opposite stages of contact with liquid and require separate methods. The companion note on water-repellency testing in knitted fabric explains spray rating, resistance to surface wetting, finish durability, and why penetration remains a distinct property.