Forensic analysis of white automotive paint of same manufacturer with Raman spectroscopy and chemometrics

Discriminating paints of the same color has always been a challenge in automotive paint examination. The process is even more difficult when these paints originate from the same manufacturer and color. Raman spectroscopy is an effective and non-destructive method that is commonly used to differentiate automotive paint. This method is often used to provide a reliable information about pigments and extenders contained in topcoats and is barely used to examine other layers of paints. In this study, A total of 54 white automotive paints from one single manufacturer (Volkswagen) were prepared and analyzed by Raman Spectroscopy. Each layer of the samples was measured in order to evaluate if Raman spectroscopy can provide good discrimination power. Statistical methods were used to characterize and classify these samples. Correlations between paint characteristics and discriminating factors (such as model, topcoat color code, production year, and assembly plant) were also investigated to get a deeper understanding of automotive paints. This article seeks to address the question: How effectively can Raman spectroscopy differentiate OEM paint from mass-produced vehicles of the same color, manufactured by the same make?image