Abstract
Two types of fabric, a tightly constructed worsted and a woolen of more open con struction, have been milled in laboratory stocks. Curves of (i) shrinkage in both warp and weft directions, as a function of time, and (ii) the mean displacement d of those fiber portions which have moved, also as a function of time, have been determined for each fabric. In the case of the worsted, the latter curve is linear for the first 5 hr of milling, although the former shows acceleration of the rate of shrinkage at about 2 1/2 hr. This indicates that fiber displacement is the primary result of milling and that shrinkage is a secondary result. From these curves the curve of linear shrinkage against d has been determined for each fabric. For the worsted this curve, after d has been corrected for shrinkage, consists of two linear regions. Their intersection marks a change in the mechanism of felting, which is also revealed by the appearance of straightened lengths of fibers and subsequently by the acceleration in the shrinkage-time curve.
The configuration of the fibers as milling proceeds has been studied, and in the case of the worsted fabric additional curves have been determined, relating the fraction of the total fiber length which is straightened to the duration of milling, to d, and to the linear shrinkage.
The induction period, an interval at the beginning of milling during which no shrinkage occurs, is also discussed.
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