A Non-Destructive Method for Assessing Interior and Surface Hair Damage by Near Infrared Spectroscopy

This paper reports a non-destructive method for evaluating hair interior and surface damage based on near-infrared (NIR) diffuse reflectance (DR) spectroscopy. It is important to know the extent of chemical damage in the interior and surface proteins of the hair in order to choose an appropriate restoration agent or chemical treatment. Unfortunately, though there are many simple and non-destructive methods for evaluating the hair surface, the existing evaluation methods for monitoring chemical changes in the interior proteins are very complicated and destructive. Therefore, we have attempted to develop a new non-destructive method to evaluate the damage to the hair interior and surface simultaneously by using NIR-DR spectroscopy. The key to this study was that the combination of NIR-DR spectroscopy and principal component analysis (PCA) were applied to development of an evaluation of hair damage and we found the most suitable wavenumber region (5060-4500cm-1) for the evaluation of hair damage. In this study, we developed a new evaluation method that can indicate hair interior and surface damage conditions induced by chemical treatments in a simple, rapid, non-destructive manner based on NIR-DR spectroscopy by putting a fiber probe on hair.