The zeta potentials of wools treated by chlorination and by chlorine/Hercosett have been found to differ markedly. Fabrics made from the two wools and from a blend of the two were washed together at two values of pH. Under these conditions there is no evidence that surface charge effects make any contribution to felting shrinkage.
Balanced illumination techniques have been used for many years to improve the detection efficiency for colored fiber contaminants in a white fiber mass, e.g., white wool top. The individual fibers in a mass of white wool are essentially transparent, and their images can be partially suppressed by a suitable choice of illumination to increase the contrast of the colored fibers. This paper uses geometrical optics to explain the partial suppression of images formed by transparent fibers under balanced illumination. The paper also shows that these images can be completely suppressed in the ideal situation, where transparent fibers with circular cross section are completely surrounded by a uniformly diffuse source of illumination. The performance of a balanced illumination system can be optimized by choosing illumination conditions that conform more closely to this ideal situation.
Fleeces, top and finished fabric processed from white Merino (fibre recipient)
ewes, run in close contact for 2 weeks, with either Awassi, black Merino or
white Merino control (fibre donor) ewes, were analysed for the presence of
contaminant fibres (pigmented, urine stained and kemp). Kemp and pigmented
fibres were transferred from Awassi and black Merino sheep into the fleeces of
the recipient ewes. The concentration of kemp and pigmented fibres found in
the fleeces, top and fabric of the black Merino treatment was substantially
greater than the Awassi and Merino control groups which were not different
from each other. Fibres transferred from the black Merino group were darker
than those from Awassi sheep and thus posed a greater potential contamination
threat. Contaminant fibres which are structurally different from the wool bulk
(such as kemp) tend to be removed during worsted processing, while those with
similar dimensions (such as pigmented Merino wool fibres) are more likely to
persist in the system and appear as contaminants in worsted fabric.
The dependence of felting shrinkage rate upon yarn count, cover factor, shrink proofing level, and severity of washing action has been examined, using plain-knitted wool fabrics. The investigation was a factorial arrangement with 54 combinations of factors for each of two shrink-proofing treatments. The results were subjected to analyses of variance. The felting shrinkage rate was lowered by increasing the cover factor, by increasing the level of shrinkproofing treatment, and by decreasing the severity of washing. Samples made from fine yarn shrank at a lower rate than those of heavier count. There were two significant interactions between the factors for each set of data. These showed that (i) the shrinkage rates of the fabrics made from the fine yarns were more sensitive to change of cover factor than were those of the coarser yams, and (ii) an increased level of shrinkproofing treatment increased the sensitivity of the samples to the severity of the mechanical agitation during washing. The results may be used for predicting shrinkage rates in knitted fabrics. An example is given.
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