Forensic Paint Examination

Abstract

The identification and characterization of paint evidence is important from both the forensic and conservation perspectives. Paints are one of the most complex mixtures formulated by the chemical industry or by individual artists, utilizing thousands of different kinds of raw materials and intermediates. The diversity of coatings, if exploited fully, increases the distinctiveness and hence the evidential value of any given paint. It is essential that the forensic paint analyst has a basic understanding of paint chemistry and end-use application methods in order to be able to convey context to the interpretation of the occurrence of a particular component in the evidence. Zinc-rich paints and zinc oxide pigments have also been used in a variety of coating applications to protect metal substrates from the effects of corrosion, with the most important zinc anticorrosive pigment in forensic paint examination being zinc phosphate, Zn3(PO4)2. The majority of cases requiring forensic characterization of paint will be in the form of a dry film.