Using paint to investigate fires: an ATR-IR study of the degradation of paint samples upon heating

Roberts, K., Almond, M. and Bond, J. W. (2013) Using paint to investigate fires: an ATR-IR study of the degradation of paint samples upon heating. Journal of Forensic Sciences, 58 (2). pp. 495-499. ISSN 0022-1198 doi: 10.1111/1556-4029.12049

Abstract/Summary

Fire investigation is a challenging area for the forensic investigator. The aim of this work was to use spectral changes to paint samples to estimate the temperatures to which a paint has been heated. Five paint samples (one clay paint, two car paints, one metallic paint, and one matt emulsion) have been fully characterized by a combination of attenuated total reflectance Fourier transform infrared (ATR-IR), Raman, X-ray fluorescence spectroscopy and powder X-ray diffraction. The thermal decomposition of these paints has been investigated by means of ATR-IR and thermal gravimetric analysis. Clear temperature markers are observed in the ATR-IR spectra namely: loss of m(C = O) band, >300°C; appearance of water bands on cooling, >500°C; alterations to m(Si–O) bands due to dehydration of silicate clays, >700°C; diminution of m(CO3) and d(CO3) modes of CaCO3, >950°C. We suggest the possible use of portable ATR-IR for nondestructive, in situ analysis of paints.