Forensic Science Applications of Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS): IV. Direct Analysis of Metallic Paints - Sampling Considerations

• NCJ Number: 115493
• Journal: Journal of Forensic Science Volume: 34 Issue: 1 Dated: (January 1989) Pages: 164-179
• Author(s): E M Suzuki
• Date Published: 1989
• Length: 16 pages
• Publication Format: Article
• Publication Type: Report (Study/Research)
• Language: English
• Country: United States of America
• Note: Preliminary reports on this work were presented at the FBI International Symposium on the Analysis and Identification of Polymers, Quantico (Virginia), August 1984, and at the 37th Annual Meeting of the American Academy of Forensic Sciences, Las Vegas, February 11-16, 1985.

Annotation

Many metallic paints, which are commonly used for automotive finishes, can be sampled directly using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS).

Abstract

The density of metallic flakes used in a particular paint is the primary factor determining the applicability of this method. Specular reflectance, which often limits the usefulness of data obtained from direct DRIFTS sampling, can be mostly eliminated through selective changes in the geometry of the diffuse reflectance accessory. The nature of this direct sampling method depends on the density of the metallic flakes, and a Kubelka-Munk-type reflectance is not the only process involved. For paints having a high density of metallic flakes, spectra of chips as small as 0.5 by 0.5 mm can be obtained. Metallic paints having a basecoat/clearcoat finish can also be sampled using this method, but the clearcoat or primer layer must first be removed. (Author abstract)