2. Experimental
2.1 Materials
Tresses of virgin dark brown hair, approximately 4g and 20cm long, were prepared in parallel and grey hair was removed so as to obtain more uniform and accurate result. The hair samples were washed by shampoo followed by conditioner and dried at room temperature. The samples were then conditioned at 21 ± 1oC with relative humidity of 65 ± 2% for 24 hours prior to further treatment.