HAIR BLEACHING AND WAVING 167 58.3 55 52.1 9.0 in Vs so Vs so3 in CySO 3 L5.9 /-,.2.8 Vas $0 3 in CySO•- I I I I l m ..:!' ,,o t-- c• o "• • c'• '•- o o Wovenumbers Figure 5. Section of a single fiber FTIR-spectrum of European brown human hair measured with the high-pressure diamond cell. Upper spectrum: untreated hair lower spectrum: commercially bleached hair (Schumacher-Hamedat (17)). or bromates as reoxidation agents. Although permanent waving has been in use for more than forty years, some details of the mechanism of the process still require clarifi- cat{on. REDUCTION STEP OF PERMANENT WAVING The thioglycollate attacks specifically the disulfide bonds in hair and reduces protein- combined cystine to cysteine. The resulting degree of reduction is of fundamental im- portance for a consideration of the events during waving. High degrees of reduction cause an overprocessing of hair, whereas too low degrees result in insufficient develop- ment of curl.

168 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 1.Dimension - Seporofion Potomelet. Chorge -I- 1.1 -6 at pH 3 -- c UNTREATEO Figure 6. Fluorograph of a two-dimensional electrophoresis pattern of untreated European brown hair (Bindewald (25)).