Figure 14 illustrates the tensile strength result of the perming damaged hair samples. The breaking load of the hair samples shows a descending trend when subject to the perming treatments. It slightly drops from 94.13N of the control sample to 89.25N of the perming treatment at pH 7, which is relatively a gentle perming lotion. The breaking load continuously decreases to 78.53N and 76.28N when the perming lotions are at pH 9 and pH 10 respectively. It is obvious that the pH of perming lotion has a strong relation with the tensile strength of hair, i.e. the breaking load declines when the pH of perming lotion is more alkaline.