ISOLATION OF CUTICLE 287 i i 3.5tUntreate d 3 2.5 2 DS-1 1.5- 1- 0.5- DS-3 DS-4 I I • I •- 0 30 - 40 DS-2 10 20 Treatment Time at 50 øC (hr) Figure 4. Relation between the change in cuticle thickness and treatment time in 5% KOH/1-butanol at 50øC. decrease in cuticle thickness is estimated from the whole-cross-sectional area in SEM microphotographs. The average diameter of 72.6 ñ 5.0 pom in the untreated hair with a ten-layer cuticle, 56.9 - 4.4 pom for DS-3, and 50.4 -+- 4.1 pom for DS-4. This indicates the complete elimination of cuticle for DS-3 and DS-4 partial dissolution of the cortical cells is also postulated for both specimens. This enables one to estimate the treatment time to obtain a wholly descaled hair without any dissolution of the cortex. According to the results reported by Taki (3), the surface of wool fiber was smooth, without overlap of cuticle cells, when treated in 6% KOH/1-butanol for 17 hours at 50øC with a mild agitation. The authors assigned the specimen thus treated as descaled wool without degradation in the cortical cells (3,4). Since the thickness of the cuticle layer of wool is about 0.5 pom, the time of treatment required for removing only one or two cuticle layers seems to be too long when compared with the present results for human hair. This is interesting because these results may indicate a difference between wool and human hair in the reactivity with KOH/1-butanol.

288 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS FT-IR MEASUREMENTS Figure 5 shows the transmission spectra of the inside of the cortex for the untreated and DS-3 hair as measured by the FT-IR microscope. The larger peaks centered at 1650 --1 --1 --1 cm 1530 cm , and 1240 cm are Amide I, Amide II, and Amide III bands, respectively. There is no change between them, suggesting that the structure and chem- ical composition inside the cortex are not largely affected by KOH/1-butanol. Figure 6 shows the diffuse reflectance spectra from the assembly of the surface sections for the untreated DS-3 and DS-4 hairs. Appreciable changes in the spectrum are observed in the region from 1000 cm- 1 to 1100 cm- • Treatment with KOH/1-butanol may cause a . chemical change in several amino acid residues, particularly for cystine and cystein. The small band appeared at 1022 cm-• for DS-3 and at 1076 cm-• for DS-4. IR spectra of the oxidized wool and hair were reported (15-17), and the peaks at 1022 cm-t and at 1071 cm- 1 were assigned to S-sulfonate (Bunte salt) and the cystine monoxide band, respectively. 2 1.5 1800 I I 1600 Untreated DS-3 1400 1200 1000 Wavenumber (cm Figure 5. FT-IR spectra of inside hair (cortex) of untreated (--) and DS-3 ( .... ) hairs.