Hair Damage 384 composition. Taking advantage of accrued knowledge on the behavior of proteins during heating, and of continuous improvement in techniques such as differential thermal analysis (DTA) and DSC, then the heat effects on keratin fibers and the “melting” behavior of α-form crystallites becomes a powerful analytical tool that is important for understanding the fine structure and associated physical properties. Both DSC and DTA record the thermal behavior of a sample under controlled heating in comparison to a reference material. The thermal behavior of keratin fibers was studied over time both “dry” (after allowing the moisture to evaporate by heating) and “wet” (using closed pans in which water is added and everything is kept under the corresponding pressure). The “dry” studies show evidence of two endothermic peaks above 200°C. Heating hair fibers in silicon oil, and watched using microscopy, allowed for observation of two different overlapping processes: pyrolysis of the matrix and “melting” of the alpha-helix. The “evaporation” of the matrix was documented by images captured during the experiments, as shown in Figure 6.48 238°C 235.5°C 233.5°C 227°C 210°C 254°C Figure 6. Snapshots showing the behavior of keratin snippets heated in silicon oil with 10 K/ min. The temperature is indicated on each photo, respectively.