For panels with finishes having high densities of metallic flakes, spectra identical to those obtained using conventional transmittance techniques may be obtained with DRIFTS and relatively minor spectral features may be used to distinguish between different topcoats. For panels with finishes having low densities of metallic flakes, information about the minor constituents of the topcoat and the presence of specific pigments in the undercoats is also obtained in certain cases. These data, likewise, may serve to differentiate between different finish systems. (Author abstract)