Wetting and Wicking properties of fibers

Capillarity and Wicking

Wicking simple means the capillary movement of moisture within fabric structure. Wicking can only occur when a liquid wets the fibers assembled within the capillary spaces between them. Capillary forces are responsible to drive the liquid in capillary spaces. Wicking will not begin when the moisture content of the wet fabric is less than that of 30% moisture regain. The fiber surface properties, pore structure, structure of component yarn and the fabric are the main determinants wicking properties.

The term wicking has been the subject of many research papers. In general, wicking takes place when a liquid travels along the surface of the fiber but is not absorbed into the fiber. Physically, wicking is the spontaneous flow of a liquid in a porous substrate, driven by capillary forces.

This type of flow in any porous medium, caused by capillary action, is governed by the properties of the liquid, liquid-medium surface interactions, and geometric configurations of the pore structure in the medium. Liquid properties such as surface tension, viscosity, and density as well as the surface wetting forces of the fibers are known or can be experimentally determined, but the pore structure of a fibrous medium is complicated and much more difficult to quantify. The complexity of a fabric structure makes it impossible to measure an accurate pore structure. Furthermore, movement and interaction of a liquid through pores can cause both shifting of fibers and changes in pore structure. Changes in fiber properties caused by wetting can significantly alter liquid movement The wicked moisture spreads throughout the fabric allowing the moisture to easily evaporate.

The behavior of a given textile during its contact with water (or with the liquid generally) is one of the important properties of textiles. Wicking especially influences the consumer properties of textiles. If the liquid rises (by absorption) in fabric, it can be used as a liquid perspiration outlet from the skin, for the production of hand towels and dishcloths, textiles for cleaning works, and many other such applications. Wicking makes it possible to use textiles for a series of other special applications: wicks for candles and lamps with oil, or some modern flameproof finishing for housing textiles.

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