Paint database system of automotive topcoats for forensic purposes

Abstract

Automotive paint traces are one of common physical evidence found at crime scene. The paint traces that come in the size of chip or as a smear found on the road or on the clothing of the victim involved in hit-and-run accident cases can be compared with the paint sample taken from suspected car in order to establish the origin of the paint. The automotive paint sample from 50 Perodua cars were collected from several workshops, auction yards, salvaged used parts and the police station’s accident vehicles’ yard in Perlis and Selangor. From the 50 automotive paint samples collected, a paint database namely My-Automobile Paint Database Version 1 was developed based on the analyses conducted, which are non-destructive microscopic examination followed by non-destructive infrared spectroscopy and destructive solubility tests. The microscopic examination was conducted using stereomicroscope equipped with a digital camera to examined layer characteristics of paint fragments in terms of colour, number of layers and thickness of each layer. The binder or resins and pigment present in the paint formulation were identified using spectroscopic techniques of FTIR in transmittance and ATR mode. While the solubility test was conducted using various solvents such as chloroform, acetone, concentrated sulphuric acid, xylene, glacial acetic acid and diphenylamine solution in order to identify the solubility parameters of each paint fragment, which are degree of solubility, colour changes and texture changes. My-Automobile Paint Database Version 1 was developed using Microsoft Visual C# 2010 Express with the Microsoft SQL Server 2008 Express as the database storage and this database is capable to provide a possible match data when comparing the unknown paint received from the crime scene to the known paint in the database. Therefore, the origin of the unknown paint can be revealed