HAIR STRAIGHTENING USING AN AUTOMATED FLAT IRON 125 STRAIGHTENING PERMANENCY In Figure 5, the hair tress photographs are shown at different cycles and different temperatures. In each square picture, the control tress with no silicone was on the left and the tress treated with silicone was on the right. A progressive straightening was observed as temperature and number of cycles increased. The ironing experiment was stopped when permanent straightening was achieved. On the left upper corner of the picture display, hair tresses treated for one cycle and two cycles at 122°C and 144°C, respectively, were curly and puffy. In contrast, at 175°C, a clear decrease in the tress volume and increased straightening was observed at one cycle and two cycles. A similar level of straightening was obtained at 154°C and 144°C with 5 cycles and 10 cycles, respectively. In contrast, after 10 cycles at 122°C, the hair was still curly. In general, at all temperatures and cycles, the silicone treatment provided a better fi ber alignment and reduction of tress volume. Figure 5. Tress visual after the iron cycles, wash, and storage for 30 min in 90% RH chamber as a function of the hair temperature. On the left, cycle numbers. In each square picture, the control tress is on the left, and the silicone treated tress is on the right. {Note: Test data. Actual results may vary.}

JOURNAL OF COSMETIC SCIENCE 126 DSC DATA Multiple iron cycles. DSC analyses were performed for the samples shown in Figure 5. Ex- amples of DSC fl ow curves corresponding to tresses A, B, and C are shown in Figure 6. Curly sample A treated at 122°C displayed a sharp peak similar to untreated hair, whereas the straight samples (B and C) had much shallower endotherm peaks, indicating a de- crease of α-keratin microfi lament crystallinity. The complete set of DSC data is shown in Table II. In general, enthalpy values decreased as the number of cycles and iron cycle temperature increased. Td shift was quite small Figure 6. Examples of DSC curves of samples A, B, and C shown in Figure 5 and an untreated hair sample. For each sample two DSC curves (2 pans) are displayed. {Note: Test data. Actual results may vary.} Table II Denaturation Temperature, Td, and Enthalpy, ΔH, for Hair Samples Ironed Multiple Times at Different Temperatures (Hair Temperature was Probed at 1 cm above the Iron) Number of cycles Cycle temperature 122°C 144°C 154°C 175°C Td (°C) ΔH (J/g) Td (°C) ΔH (J/g) Td (°C) ΔH (J/g) Td (°C) ΔH (J/g) 2× water 172.7 5.3 173.7 5.7 173.2 4.7 169.9 4.8 2× silicone 173.5 5.0 173.7 5.7 173.6 5.4 168.0 2.0 5× water 173.7 3.7 172.7 3.4 173.1 2.8 5× silicone 174.2 4.3 173.0 3.6 172.8 2.6 10× water 174.4 2.8 172.9 3.6 10× silicone 174.0 4.3 172.0 3.6