If you are interested in how your products, or styling devices, might be affecting hair proteins and lipids and causing hair damage, then you might consider using Fourier transform infrared spectroscopy (FT-IR) or Raman spectroscopy.

FT-IR and Raman spectroscopy are techniques that can detect changes in the chemical composition and internal structures of hair.  These methods can either be used over large surface areas to measure overall changes in a sample, or they can be used to measure changes in tiny, focused parts.  Thousands of these focused measurements can be built-up into 2D, and even 3D, images that can show the distribution of different components in the hair.  FT-IR and Raman spectroscopy are widely used to investigate chemical damage to proteins, changes in protein cross-linking, changes in hair keratin structures and the levels of hair lipids, which can be used to investigate damage prevention and repair.