Mapping Of Human Hair Hydration. An Innovative Visual Tool For Claim Substantiation

Author: Samara Eberlin

Published at: August 24, 2023

35 Congresso Brasileiro de Cosmetologia, São Paulo, 13-15 Junho 2023

Angela Cristina Vargas Calle; Alzira Xavier Pinto Diniz; Nathana Cindy Barros Silva Ramos; Caroline Vieira Hercolino; Victoria Gonçalves; Jussarah Viana; Nelson Luis Perassinoto; Adriano Pinheiro.

One of the main complaints from consumers regarding hair fiber is hair hydration, which is why various efforts have been made to verify if the application of cosmetic products to hair alters its water content. One of the techniques used to quantify this effect is differential scanning calorimetry - DSC. This technique allows the measurement of the enthalpy of water vaporization associated with the hair. In the traditional form, to perform the DSC test, a small sample of hair, which is considered representative of the entire sample, is placed in the equipment and subjected to a temperature variation between 25 and 180°C. Although the result is a good estimate of what happens in the hair as a whole, it assumes that the fiber is homogeneous from root to tip; however, the hair is a structure that is generated in the hair follicle and grows approximately 0.4mm per day, so that the hair that is closer to the tips is older than the hair near the root and therefore has been exposed to more accumulated damage. This information allows us to infer that little is known about the effect on the enthalpy of vaporization of cosmetic products along the hair. In this work, hair strands, after being treated with cosmetic products, were sectioned into 5 equal parts and each section was subjected to measurements of enthalpy of water vaporization by DSC. The DSC results were interpolated with images of the strands, taken after the application of the treatments, using a new software developed by our group. The software assigns a color for each enthalpy value on a scale of 100 to 300 mJ/mg, corresponding to blue for the value of 300 mJ/mg (more hydrated) and red for the value of 100 mJ/mg (less hydrated), generating a hydration map that reflects the statistical analyses. The methodology developed enables the quantification of the enthalpy of vaporization along the strand and allows easy visualization of the results obtained.