THE most striking property of the wool fibre is its ability always to return to its original length after stretching in cold water. If, however, a fibre is steamed in the strained position, it shows no tendency to return to its original length in cold water. So far as I am aware, it has hitherto been found impossible to induce such fibres to return to their original length, although partial recovery occurs on re-steaming in the absence of tension. During the course of another investigation, however, I have recently found that fibres which have taken a permanent set of the kind just described, recover the property of perfect elasticity in caustic soda solutions. For example, a fibre which had been stretched and steamed for 15 minutes at 47.4 per cent extension, returned to its original length in 14 minutes in 0.15 N caustic soda solution. Contraction does not cease when the original length is attained, but continues beyond this point until a real shrinkage of about 10 per cent of the original length is observed. The rate of recovery increases with the strength of the solution, but is measurable even in 0.01 N caustic soda. The discovery opens up a number of possibilities in regard to ‘finishing’ processes in the wool textile trade, but of even greater significance is the contribution which it makes to knowledge of the elastic phase in the wool fibre and the changes which it undergoes during stretching and steaming. Complete details of the results and conclusions of the investigation will be described in another place.
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SPEAKMAN, J. The Perfect Elasticity of Wool. Nature 124, 948 (1929). https://doi.org/10.1038/124948b0