Associations between the physiological basis of fabric-evoked prickle, fiber and yarn characteristics and the Wool ComfortMeter value

Abstract

The association between the incidents counted by the measurement wire of the Wool ComfortMeter (WCM) and the previously published neurophysiological basis for fabric-evoked prickle have been investigated for lightweight knitted woolen fabrics. The fiber lengths and diameters capable of triggering the fabric-evoked prickle sensation were calculated using Euler’s buckling formula, and it is suggested that fibers as fine as 10 µm are capable of triggering the prickle response if they have a short enough free length protruding from the surface. Good agreement was found between the sensory assessed human prickle sensation and the wearer prickle response predicted using the WCM outputs, especially when the latter were transformed using Stevens’s Psychophysical Power Law.

Effects of variation in wool fiber curvature and yarn hairiness on sensorial assessment of knitted fabrics

“…[20][21][22] The reported importance of the coarse fibers in evoking prickle discomfort appears to be based on an incorrect interpretation of Euler's law, as recent investigations have shown that fibers as fine as 10 mm could cause prickle discomfort provided their length was sufficiently short. 23 This insight as to which fibers may be responsible for prickle sensations helps explain the observation that in woven fabrics, in order to achieve the equivalent comfort of knitted fabrics, a woven fabric needs to be made from wool with a 3 mm finer MFD. 24 As Naebe et al 23 explained, this is because the yarns for woven fabric have a higher twist, so the effective length of fibers protruding above the surface of the yarn are less than if the same top was spun with lower twist for knitting yarns.…”

“…23 This insight as to which fibers may be responsible for prickle sensations helps explain the observation that in woven fabrics, in order to achieve the equivalent comfort of knitted fabrics, a woven fabric needs to be made from wool with a 3 mm finer MFD. 24 As Naebe et al 23 explained, this is because the yarns for woven fabric have a higher twist, so the effective length of fibers protruding above the surface of the yarn are less than if the same top was spun with lower twist for knitting yarns. Therefore, the stiffness and capacity of the fibers to excite nerve endings is significantly increased in yarns spun for weaving.…”

“…Another approach is to use the Wool ComfortMeter that has been developed at the CSIRO, Materials Science and Engineering, Belmont, Australia, as a method to provide objective laboratory assessment of the perception of garment-induced prickle sensations. 13,18,23,25,37,41,42 The instrument uses a measurement wire mounted in a recording head, which scans the surface of the fabric, interacting with fibers protruding from the fabric surface. Since the instrument has been designed to detect changes in wool fiber bending stiffness, 42 it is expected to be able to detect the changes in comfort with variations in fiber properties.…”

Relationships between sleeve trial and wearer trial assessment of discomfort and objective measurements

“…The Wool ComfortMeter values ranged from 13 to 855, the upper value exceeding the target range for comfortable fabrics. 11,17,31 Generally there was a range in Wool HandleMeter parameters of 3 to 5 units. For sleeve trial assessments, the range was about 27 to 50 units, with the largest range and variation in skin feel.…”

Fabric handle properties of superfine wool fabrics with different fibre curvature, cashmere content and knitting tightness

“…Comfort involves physical interaction between the human body, the fabric and the external environment, while handle is the reaction to the mechanical interactions between human skin and the fabric, where both the fabric surface and the material bulk are being spontaneously evaluated by external body movement. In recent studies, it was shown that prickle discomfort is driven by the mean fibre diameter (MFD) of the wool and the length of fibres protruding from the surface of the fabric or yarn (McGregor, Doughty, Thompson, Naebe, & Tester, 2015;Naebe, McGregor, Swan, & Tester, 2015).…”