Authentication of postal pieces by spatially resolved x-ray fluorescence analysis

Abstract

The authentication of philatelic pieces is a complicated task that usually requires several processes, including the inspection and evaluation by experts, the observation with optical microscopes, UV assessments and IR examinations; application of Raman spectroscopy, EPMA and DXR techniques have been reported. There are very few references of the application of x-ray fluorescence (XRF) techniques to philately, and certainly applications of this technique to philately in Argentina are unknown. The utilization of XRF in philately can be very diverse but its basic application consists of qualitative (quantitative if possible) elemental determination of the components of the different inks used, on stamps, postmarks or postage stamps. One of the most immediate analyses consists of studying the inks of the postmarks. In this work, we present qualitative analysis of postmark inks of several postal pieces by spatially resolved x-ray fluorescence analysis. Some of them were recognized by experts as authentic ones and others as fake ones. The measurements were carried out using a conventional spectrometer with sample-positioning stages; microbeams were attained by microcollimators and also a monocapillary. The results obtained in this work indicate that spatially resolved XRF is a suitable technique for the authentication of postal pieces through the identification of the elements that constitute inks. Copyright © 2006 John Wiley & Sons, Ltd.