A Scientific Analysis of the First Issues of Chile 1853–1862, London Printing

The London printings of the Chilean postage stamps between 1853 and 1862 were examined using analytical instruments available at the Smithsonian Institution. There are four broad major technical areas important to philatelic research: color science (colorimetry and luminescence), paper chemistry (composition, thickness, and roughness), ink chemistry (pigment and binder composition), and printing methods (engraving and lithography). The analyses performed in this study address these four broad major technical areas while providing an understanding of the characteristics of these stamps, showing the utility and capability of forensic and scientific equipment available to philatelic researchers and offering an effective, rapid, and nondestructive way of identifying the pigments and dyes in the inks and papers used. Xray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), colorimetry, and Xray diffraction (XRD) were all used on the stamps without damaging the samples. In some cases different XRF and FTIR manufacturers were used to compare the capabilities of different instruments in analytical philately. Because of the significant sensitivity differences of the equipment, the results are often complementary. Only by combining the results from several pieces of equipment was it possible to gather enough information to fully differentiate between the stamps and to obtain the complete characterization for each ink, pigment, and paper. This paper gives guidance as to which scientific instruments and methods are most useful when examining different characteristics of stamps. The results show the inks vary considerably between different printings. In the various red inks used by Perkins, Bacon & Co. the variation in the amounts of iron, calcium, and potassium used in the stamps examined show printer experimentation in the recipe used to make the ink. However, comparison between two blue inks used between 1853 and 1862 show little variation in the components used. This suggests much of the variation in the red ink recipe is due to Perkins, Bacon & Co. trying to solve the bluing problem present in many of their stamps during this time period.