Application of microspectrometry in the visible range to differentiation of car paints for forensic purposes

The first step to be taken in forensic investigation of paint samples is their comparative analysis in terms of colour. Microspectrometers allow an objective measurement of colour as opposed to the subjective results of visual colour comparison. In this paper, results of assessment of the usefulness of spectral information obtained by Vis microspectrometry in differentiation of small paint coat fragments for criminalistic purposes are presented. Fragments of red, blue, brown and green car paints were measured in reflectance mode both directly on a cross-section of the paint chip and via the top layer using a light beam falling perpendicular to the top surface of the sample, and in transmittance mode. It was found that the results obtained were reproducible. The variation in colour of paint samples measured via the top layer was greater. The reflectance curve obtained constitutes a representation of colour.