NCJ Number
213746
Journal
Journal of Forensic Sciences Volume: 51 Issue: 2 Dated: March 2006 Pages: 340-343
Date Published
March 2006
Length
4 pages
Annotation
This study analyzed 160 apparently achromatic (a single color) automotive paints with the use of visible microspectrophotometry (MSP), in order to determine whether secondary color pigments were present.
Abstract
The majority of the samples produced a featureless curve in the visible range, which is characteristic of the flat absorption expected with achromatic paint samples. In the black-paint sample set, 11 of the 40 samples provided evidence of secondary paint pigments. In the gray/silver sample set, 10 of the 40 samples showed some color variation. Eight of these ten samples resulted in stronger and more distinct absorbance throughout the entire visible region. These findings indicate that compared with polarizing light microscopy (PLM), MSP can provide additional information on the presence of secondary color pigments present in apparently single-color paints. MSP should be regularly included in analyses of automotive paints, particularly when there are black and gray/silver topcoats. The study used 120 automotive paint samples from damaged vehicle panels obtained from salvage yards and body shops. Forty samples each were obtained from vehicles with white, gray/silver, and black topcoats. An additional 40 samples of gray undercoat were obtained from the original vehicular samples. Examination of the paints with PLM ensured proper preparation and the absence of contamination by adjacent layers. The presence of metallic flake or visible pigments was also recorded. Visible MSP was used to allow the distinguishing of paint samples by their interaction with light in the visible region of the electromagnetic spectrum. Samples were analyzed in five locations, with each location subjected to an average of 10 scans. 1 table, 4 figures, and 6 references