Characterization of Paint by Fourier-Transform Infrared Spectroscopy, Raman Microscopy, and Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy

The identification of automotive coatings has become important for forensic scientists to trace suspects. Popular automotive coatings include acrylic, amino, alkyd, nitro, and polyurethane paints. Various pigments and additives are added to the coatings, which may create difficulty in characterization of paint evidence. In this study, Fourier-transform infrared spectroscopy, Raman spectroscopy and scanning electron microscopy-energy dispersive X-ray spectroscopy were used to characterize an eleven-layer paint sample. Most layers were only a few micrometers thick. Infrared spectroscopy has several advantages in identifying resins and additives, while Raman is more effective in characterizing additives and inorganic pigments. Scanning electron microscopy-energy dispersive X-ray spectroscopy provides elemental analysis information. The results reveal that the combination of these techniques provides more accurate paint identification than using them separately.