PERMANENT SETTING OF HAIR 211 formic acid and their mechanical behavior in water at room temperature to have less than 10% cleavage of their disulfide bonds (4). When a low concentration of ammonium thioglycollate is used for steps 1-3, the sulfhydril concentration is low due to the low disulfide bond cleavage, as in the above example. Reducing the temperature of the hair to room temperature, with a concurrent washing away of the reducing agent, results in the protein structure being set. That is, at room temperature, the hair fibers become mechanically stiff because the former mo- bile protein chains are now in a "glassy" state. Under these circumstances, step 4, the oxidation step in the example quoted above, was no longer necessary. It has been re- placed by the lowering of the temperature of the curl to room temperature. Human hair was permanently waved using high temperature, short time, and low con- centration of ammonium thioglycollate. This minimized the amount of disulfide bond reduction of the fibers. It removed the need to reform the cleaved disulfide bonds, i.e., eliminated the neutralization step at the completion of the perm process. The resulting permed hair, both in appearance and in touch, demonstrated a major reduction in changes produced, as compared to standard permanent waving procedures. Force-exten- sion tests for individual hair fibers in water at room temperature, before and after this high temperature permanent waving technique, showed a mechanical weakening of the fibers of under 10%. If these hair fibers were then reoxidized to reform the cleaved disulfides, the fibers were mechanically weakened to an average 17% below their pre- perming tests in water. This result strongly suggests that more mechanical damage is done to the hair fibers by the oxidation, outweighing the benefit of disu!fide bond reformation. The permanently waved hair samples were washed in water heated to various tempera- tures. Up to temperatures of 60øC, no relaxation of the wave set was observable after washing. Above 60øC, however, the wave set relaxed progressively with temperature increase. Repeated washings in water at 45øC, corresponding to the expected maximum temperature for the washing of human hair, showed no observable relaxation of the wave set for samples washed once a week over a period of 12 months. The general conclusion for the work reported here is as follows: The protein chain rearrangement necessary to restructure the hair fiber into a waved configuration can be carried out for a short time period, at an elevated temperature and with a minimum of disulfide bond breakdown, i.e., a low ammonium thioglycollate concentration. The wave set is stable at room temperature without any need for reoxidation of cleaved disulfides. As a consequence, it is feasible to eliminate the oxidation step (step 4) of the normal perm setting procedure. This reduces the time of the setting procedure by about 30 minutes. Over and above this time advantage, the hair has considerably less chem- ical damage than that which is produced by standard permanent waving procedures. This is because of the requirement for a much lower disulfide cleavage in steps 1-3 and an elimination of step 4. The hair looks and feels better when permed by this tech- nique. Other advantages also follow from the use of lower chemical concentrations in the waving lotions. There is a reduction in the potential for skin burns to the client and dermatitis problems for the operatives. Because the ability exists for carrying out the complete setting procedure in a much reduced time, an individual test for set of one

212 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS hair curl becomes a simpler procedure. The work reported in this note is being ex- panded to examine the flexibility created by this lower chemical activity required to obtain a satisfactory permanent wave. REFERENCES (1) M. Feughelman, "Permanent Set in Single Wool Fibres and the Process of Recovery of Extension," in Proceedings of the 3rd International Wool Textile Research Conference, Section 2 (Paris, 1965), p. 255. (2) M. Feughelman, F. Irani, and Maurine Gan, Stress relaxation of wool fibres in different media at 96øC, Text. Res. J., 38, 1039 (1968). (3) M. Feughelman, "The Mechanism of Set in Bending of ot-Keratin Fibres," in Proceedings of the 8th International Wool Textile Research Conference (Christchurch, New Zealand, 1990), Vol. 1 p. 517. (4) M. Feughelman and B. M. Chapman, The swelling of wool fibres with reduced disulfide content in 98% formic acid, Text. Res. J., 36, 1110 (1966).