It is shown that wool fibers in which the cystine linkages have been permanently broken can be given a set in boiling water equal to that of normal fibers. Set imparted by water or steam can be released by further treatment at 10° to 20° C. above that used in setting. Boiling solutions of reducing agents begin to impart permanent set in less than 15 sec., and a very high degree of permanent set is obtained within 30 sec.A high degree of permanent set can be imparted in a short time at low temperatures by treatment of extended fibers with a solution of urea containing a reducing agent. The resultant set is greater than that obtainable with boiling water after prolonged treatment, or with boiling alkaline solutions.The results are readily explained by breakdown and reformation of hydrogen bonds following scission of some cystine linkages.

A study has been made of the effect of rate of drying, and of alternate wetting and drying, on the wrinkle recovery of fabrics of wool, wool blends, and cotton, when wrinkled in the wet state. Recovery is independent of the rate of drying, but a second-stage rapid recovery occurs at a stage in drying corresponding to loss of water from the internal fiber structure, as distinct from surface evaporation. Repeated, alternate increase and de crease of regain leads to progressive, step-wise recovery from wet wrinkling. It is probable that the energy required to give these effects originates from the swelling-deswelling associated with changes in regain.

The use of reducing agents for setting wool has been extended to give washable non-iron effects on pure wool fabrics. Initially this was accomplished by applying the Si-Ro-Set process to garments made from shrinkproofed wool. This led to flat setting of fabrics in the mill by applying a dilute solution of a reducing agent to the fabric followed by immediate steaming on a blowing machine.When preceded by shrinkproofing, this method of setting gives excellent washable non-iron effects on pure wool fabrics. Garments made from fabric treated in this way showed satisfactory laundering and wear performance in practical trials.

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