The Effect of Temperature on the Felting of Shrink-Resistant Wool

Abstract

The rate of felting of an untreated wool fabric in buffer solutions (in the presence or absence of nonionic detergent) increases with increasing temperature of the felting solu tion until a maximum rate is reached at 40-70° C. This rate then remains constant with further increase in temperature up to 90° C. The exact temperature at which the maximum is reached depends on the pH of the solution and on the action of the machine used for felting. Behavior is different in soap solutions, the maximum rate, reached at 40-50° C. being followed by a rapid decrease in rate with further increase in tempera ture up to 90°C.

With wool made shrink-resistant by industrrally used oxidation procedures, the rate reaches a maximum at 30-40° C. depending on the pH of the felting solution. The rate decreases rapidly with further increase in temperature. Relative to untreated wool, there is a contmual decrease in felting rate of the shrink-resistant wool with increasing temperature. This is due to changes in the inherent felting property of the shrink- resistant wool with temperature of the felting solution, and not to irreversible changes in wool structure brought about by chemical attack of the solutions on the treated wool.

The results emphasize the need for accurate temperature control in all felting tests and also show that best results would be obtained with shrink-resistant wool if solutions used for laundering were of high pH and at high temperatures. However, the use of such solutions at present is hunted by questions of dyefastness and possible damage to the wool.