Transfer wicking mechanisms of knitted fabrics used as undergarments for outdoor activities

ABSTRACT

This study investigates liquid transfer from fabric layer to layer and liquid interaction between different fabrics in clothing systems. A higher external pressure leads to an early onset of transfer wicking. There exists an optimum value of external pressure for the maximum water transfer. The greater the water content initially held in wet fabric, the greater the amount of water transferred. For fleece fabrics, no significant transfer wicking occurs if the raised side of the dry layer contacts either side of a wet fleece fabric layer. If the smooth side of the dry layer contacts either side of the wet fleece fabric layer, the amount of water transferred from layer to layer is greater when the fabric setting is face to face rather than face to back. An investigation of liquid interaction within clothing systems shows that the amount of liquid transferred largely depends on the performance of individual fabrics as well as the way in which they contact each other. Integrated double-sided Aquator fabrics, which serve as the first layer in the clothing system, transfer more liquid from the wet layer to the clothing system than other fabrics. Introducing a fleece fabric into the clothing system where the Aquator fabrics serve as the first layer promotes liquid transfer into the clothing system, but if polyester eyelet knit fabric serves as the first layer, introducing a fleece fabric decreases the amount of liquid transfer from the wet layer to the clothing system.

At higher ambient temperatures or during strenuous bodily activity, the wearer perspires profusely so that clothing worn next to the skin becomes saturated with perspiration. Ideally, the liquid on the body surface or in the inner layer of clothing should be transferred to the outer layer so as to keep the skin dry and the liquid to evaporate from the outer layer to the environment. Also, condensation of moisture vapor may form in clothing under certain circumstances [3], which may result in liquid transfer back from the outer layer to the body, even if perspiration is not significantly present on the skin. Therefore, it is important to understand transfer wicking mechanisms in terms of wearer comfort for functional sportswear.

Research into the transfer of liquid from a wet fabric to a dry fabric when in close contact with each other was presented by Spencer-Smith in the 1970s [6]. He tested a linen drill fabric using this method and concluded that no liquid water transfer occurred between a wet and a dry fabric in contact until the regain of the wet fabric exceeded a critical value, which was about 80%. However, his testing method interrupted liquid transfer during measurements, which made it difficult to obtain absolute values of the transfer wicking rate from fabric layer to layer.

Adler et al. [1] investigated transfer wicking in cotton and polyester woven fabrics and in knits. Their conclusion was that vapor diffusion was the major mechanism of moisture transport between two layers of fabric at low moisture levels for all fabrics, and wicking did not begin until the moisture content was high, more than 30% above the regain for the woven fabrics. The knitted fabrics did not wick at all.

Crow and Osczevski [2] conducted similar transfer wicking experiments on a range of knitted and woven fabrics used for activewear. They reported that the amount of water that wicked from one layer to …