Hair Damage 370 Although the presence of elemental sulphur is not detected in hair, the presence of lanthionine and lysinolalanine as reaction products (see Figure 3) provide sound evidence for beta-elimination being the main pathway of cystine degradation.6 The pH value has less effect on the hydrogen bonding. A low pH helps in protonating the protein chains, and in so doing increases the number of hydrogen bonds per unit of molecule. For example, differences in the mechanical properties of single fibers will occur upon treatment with strong acids (HCl 6M), or with oxidizing acids (HNO 3 ).9 The Effect of Oxidative Agents Oxidants attack disulphide bonds following a proposed mechanism illustrated in Figure 4. The scheme of reactions indicates sulphonic acid as the end product, and Raman spectroscopy suggests an increase in its concentration upon oxidation of hair.10 Figure 3.