Evaluation of water absorption and transport property of fabrics

The liquid absorption and transport properties of fabrics are critical not only to the success of wet processes such as dyeing, printing and finishing, but also to the performance of products such as sports clothes, performance clothing, disposable hygiene materials and medical products. During wear, moisture in clothing has been found to be the most significant factor contributing to discomfort. The presence of sweat will increase friction between fabric and skin, trigger a clingy sensation and eventually increase the level of fatigue felt by the wearer. This problem will be even more severe for clothing worn under extreme environmental conditions or at high activity levels. Fabrics with excellent water absorption and transport properties have the potential to minimise the wetness sensation on skin, facilitate the evaporation of sweat and aid comfort. Hence, as a product developer or clothing manufacturer, it is essential to choose the appropriate measurement method to characterise the water absorption and transport properties of fabric. This paper reviews different subjective (by people–subjects) and objective (by instruments–objects) evaluation methods for assessing wetness comfort, and determining water absorption and transport properties of fabrics. Since perception of wetness is a complex process with a number of stimuli from clothing and external environments communicated by human sensory receptors, subjective assessment with its better representation of the real wear situation is preferred. The review starts by introducing human physiology, describing hepatic perception of wetness, followed by methods for use in experiments on assessor control, setting of environmental conditions, types of touch, the usual body sites for testing, and a summary of methods for measuring physiological and perception changes using psychological or psychophysical scaling procedures. Despite its advantage of more closely simulating the real wear condition, performing a subjective test is time-consuming and expensive. Its accuracy depends on the reliability of the assessors and the result may vary between assessors. Objective measurement might therefore provide an attractive alternative. In this study, details of objective instrumental measurements are summarised according to the technology applied, and include gravimetric, observation-based, optical, spectroscopic, electrical, pressure-based, magnetic resonance and temperature detection methods. The principles, advantages and limitations of each method are systematically compared and discussed. Practical recommendations are proposed, particularly for enhancing the accuracy, reproducibility and/or simplicity of the methods. The objective of this review is to present an overview of various measurement methods, both subjective and objective. It is intended to form a basis for enabling fabric engineers to choose the most suitable analytical test method(s) when developing new fabric products with respect to performance, the availability of resources, time for testing, the type of fabrics to be tested and the accuracy and precision required. Additionally, the review points to the need for researchers to develop more advanced and accurate measurement methods to characterise the absorption and transport properties of fabrics.