Programmed energy dispersive X-ray analysis of top coats of automotive paint

Elemental, qualitative, and semiquantitative analyses of 1974 U.S. automotive paints by a Finnigan Model 900F Energy Dispersive X-ray (EDX) Spectrometer are examined. This EDX analytical system incorporates a minicomputer to receive, store, and present data. The paint samples were received from the National Bureau of Standards (NBS) Law Enforcement Standards Laboratory as a collection representative of the top coats used on all U.S. manufactured automobiles in 1974. Aspects considered include EDX system stability, homogeneity of similarly catalogued samples from different NBS collections, categorization of paints by predominant constituents, and comparison of data on paint standards that were similar. Automated analysis represents an important application of forensic science to the characterization of paint samples and provides for the nondestructive analysis of a variety of materials in a large range of sample sizes and concentrations.