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Abstract
An investigation is reported of the correlation between hairiness values obtained with the Shirley Hairiness Meter and those obtained with the Digital Hairiness Meter developed by the Institute of Chemical and Textile Technology (ITOT). Twenty mohair yarns and 46 wool worsted yarns processed at SAWTRI were analysed with these two instruments. For mohair, very good correlations were obtained between the number of hairs per metre, as measured by the Shirley instrument, and the average hairiness and length data obtained with the Digital Meter (correlation coefficients between 0.95 and 0.99). For wool, the agreement between the two sets of results was not as good, the ITQT parameter correlating best with the Shirley measurement being the average length, followed by the maximum hairiness. For wool, the over-all correlation coefficients—without distinguishing between the different yarn linear densities—were 0.60 for the mean length, 0.47 for the average hairiness, and 0.40 for the average hairiness and maximum length. When the results were separated according to the yarn linear density, the correlation coefficients increased to 0.80–0.88 for the average length, 0.69–0.75 for the maximum hairiness, and 0.63–0.81 for the maximum fibre length, whereas they were insignificant for the average hairiness. An attempt was made to establish a parameter known as the ‘visible’ hairiness, but this gave satisfactory results only for the finest yarns (correlation coefficient 0.80).
In general, the number of hairs per metre as measured with the Shirley Meter correlated well with the average length as measured by the Digital Meter, provided that only yarns of the same linear density were compared. The correlation was lower for the maximum hairiness and maximum length and practically non-existent for the average hairiness, except for the mohair yarns.