No abstract

Recently developed by CSIRO for quality control and assurance of fabrics, FAST, or fabric assurance by simple testing, consists of a series of instruments that are in expensive, robust, and simple to use, and their related test methods. FAST is specifically designed for use by tailors and worsted finishers; it measures fabric properties that are closely related to the ease of garment making-up and the durability of worsted finishing. FAST- I gives a direct reading of fabric thickness over a range of loads with micrometer resolution. FAST-2 measures the fabric bending length and its bending rigidity. FAST- 3 measures fabric extensibility at low loads. Fabric shear rigidity is calculated from the 45° bias extensibility. FAST-4 is a quick test for measuring fabric dimensional stability, including both relaxation shrinkage and hygral expansion.

The relationships between wearer-assessed comfort and objectively measured comfort and handle parameters were investigated using 19 pure wool single jersey garments made of single ply yarns. Wearer trials were used to determine prickle discomfort, and whether wearers “liked” the garments. Fabrics then were objectively evaluated using the Wool HandleMeter, which measures seven primary handle attributes; and the Wool ComfortMeter (WCM), to predict a wearer's perception of fabric-evoked prickle. Wearer responses and the relationships within and between objective measurements and the effect of fibre, yarn and fabrics attributes were analysed by general linear modelling. Mean fibre diameter, fibre diameter coefficient of variation, yarn count, fabric thickness, fabric density, fabric mass per unit area and decatising affected one or more handle parameters. The best model for predicting wearer prickle discomfort accounted for 90.9% of the variance and included only terms for the WCM and WCM2. The WCM was a good predictor whereas mean fibre diameter was a poor predictor of whether wearers “liked” garments. Wearer assessment of prickle and whether or not wearers “liked” fabrics were independent of fabric handle assessment. The results indicate that the handle and comfort properties of lightweight, wool jersey fabrics can be quantified accurately using the Wool HandleMeter and the Wool ComfortMeter. For fabric handle, fibre and yarn characteristics were less important than changes in the properties of the fabric.

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.

The latest prototype version of the CSIRO-developed Comfort Meter was used to measure representative samples of all the garments used in the Sheep Cooperative Research Centre wearer trials. The average wearer prickle ratings of the garment sets were compared to the average Comfort Meter values for the garments. Comfort Meter values were strongly correlated with average prickle ratings assigned by wearers of the garments. As average wool fibre diameter and fabric knit structure were changed in the fabrics used in the wearer trials, the relationship between the Comfort Meter value and the wearer prickle rating remained highly correlated. The correlation between the Comfort Meter value and the wearer prickle rating changed for a set of fabrics in which the yarn structures were changed. A possible mechanism to explain the various relationships is proposed.

The handle properties of knitted wool fabrics were investigated using the Wool HandleMeter. The fabrics were single jersey knitted with three different loop lengths, where the yarn linear density was kept constant. The effect of a treatment using a continuous plasma treatment device was compared with untreated fabrics. The results confirm that the Wool HandleMeter is capable of differentiating between knitted single jersey fabrics with different surface treatments and loop lengths. With all seven primary handle attributes affected, plasma-treated fabrics were significantly different from untreated fabrics. Plasma treated fabrics were assessed as being rougher, harder, and heavier with a warmer and drier feeling compared with untreated fabrics. Regardless of treatment used, the effect of loop length was significant. It was shown that a shorter loop length is associated with fabrics that feel rougher, heavier and warmer.

The comfort properties of the pique and single jersey knitted wool fabrics were investigated using the Wool ComfortMeter (WCM). The fabrics were knitted in three cover factors and treated with either plasma or a silicone softening agent and were compared with untreated fabrics. Plasma treatment did not show significant effects on the comfort value. However, silicone polymer significantly reduced WCM values suggesting that the silicone coating reduced the number of protruding fibres on the fabric surface. Regardless of treatment used, pique fabrics showed a lower WCM value, and therefore were perceived to be more comfortable than the single jersey structure. While the effect of cover factor was not significant, in fitted model to predict the WCM value of fabrics, mass/unit area and fabric thickness were significant predictors along with fabric structure and finishing treatment.

This study examined the feasibility of assessing yarns with the Wool ComfortMeter (WCM) to predict the comfort properties of the corresponding single jersey-knitted fabrics. The optimum yarn arrangement to predict the comfort value of a corresponding control fabric was determined using nine wool and wool/nylon-blended yarns (mean fibre diameter range 16.5-24.9 μm) knitted into 34 different fabrics. Using a notched template, yarn winding frequencies of 1, 3, 6, 12, 25 and 50 parallel yarns were tested on the WCM. The best predictor of fabric WCM values was using 25 parallel yarns. Inclusion of knitting gauge and cover factor slightly improved predictions. This indicates that evaluation at the yarn stage would be a reliable predictor of knitted fabric comfort, and thus yarn testing would avoid the time and expense of fabric construction.