OBJECTIVE EVALUATION OF FABRIC HAND
Subjective sensory perceptions of sheet-type fibrous products (such as woven and knitted fabrics, nonwovens, paper products, leathers, and other such products) in contact with the human skin during use have long been recognized as being among the most important quality attributes for such products. It has, however, been very difficult to evaluate such perceptions, which often play a decisive role in the extent of customer satisfaction with such products, objectively by using instrumentation.
These sensory perceptions are often expressed in terms of the concept of the “hand” of a fabric. Fabric hand is defined in the textile industry as the quality of a fabric assessed by the reaction obtained from the sense of touch. People’s overall tactile sensory responses towards fabrics, defined as the fabric hand, comprise the combined effects of physical, physiological, psychological, and social factors.
The following three methods and systems are used to obtain objective evaluations of fabric characteristics in attempts to quantify subjective human sensory perceptions:
- Kawabata Evaluation System (KES): This system was developed at Kyoto University in Japan. It is used to quantify the subjective human perceptions of aspects of the “hand feel” of a fabric. It is used to measure tensile and shear properties on a Tensile and Shear Tester, pure bending properties on a Pure Bending Tester, compression properties on a Compression Tester, and surface friction and roughness on a Surface Tester. The image pasted below, summarizing the system, was reproduced with minor changes from the document to which the link was provided above. These measured mechanical properties are then related to various subjective fabric hand feel descriptors; such as stiffness, softness, fullness, smoothness, and Total Hand. There is quite good correlation between the subjective perceptions and the measured properties.
- Fabric Assurance by Simple Testing (FAST): This system was developed at the Commonwealth Scientific and Industrial Research Organization (CSIRO) in Australia. It was initially designed especially to predict the properties of wool and wool blended fabrics that affect their tailoring performance and the appearance of the tailored garments in wear. It is used both to predict such properties of fabrics and to provide information which can be related to the fabric handle. Unlike the KES system which was developed much earlier, the FAST system only measures the resistance of a fabric to deformation, and not the recovery of the fabric from deformation. However, the FAST system is claimed to be much cheaper, simpler, and more robust than the KES system, and hence to be perhaps better suited for use in an industrial environment. It consists of three instruments (compression meter, bending meter, and extension meter, which provide test results that can be recorded instantaneously and automatically) and a test method (dimensional stability test, for which the results are recorded manually). The results are plotted on a control chart to provide a Fabric Fingerprint which indicates whether the tested fabric will be suitable for the intended end use. The image pasted below, depicting how the results are summarized with this system, was reproduced with minor changes from the document to which the link was provided above.
- PhabrOmeter®: This system was developed by Nu Cybertek, Inc., in California, USA. It is the most recently developed sensory quality evaluation system for fabrics. It consists of an instrument and a software package. It implements test method AATCC TM 202:2014, “Relative Hand Value of Textiles: Instrumental Method”, to measure the “feels and looks” (sensory perceptions) of sheet-type fibrous products in contact with the human skin when in use. The main measured quantities are the relative hand value (an overall hand value relative to a given standard fabric), stiffness (how easily one can bend a fabric with one’s fingers), softness (compressibility judged by squeezing a piece of fabric in one’s hand), smoothness (how resistant the fabric is when one slides one’s fingertip across a fabric surface), wrinkle recovery rate (an indicator on how well a fabric recovers from a wrinkled state), and drape index (a parameter measured to represent the fabric drape behavior, where drape is defined is the ability of a fabric to assume a graceful appearance during use). The system is based on the pattern recognition theory. It works by extracting the quality characteristics of the product, and connecting them to the human sense, so as to provide fast and reliable quality evaluation results. The image pasted below was reproduced from the Nu Cybertek, Inc. website.