Authentication of Postal Pieces by XRF Analysis with Spatial Resolution

HECTOR JORGE SANCHEZ; M.C. VALENTINUZZI

París (Francia)

Conferencia; EXRS 2006; 2006

The authentication of philatelic pieces is a complicated task that usually requires several processes, including the inspection and evaluation of experts, the observation with optical microscopes, UV assessments and IR examinations. Everyday, the utilization of more complicated technologies is more and more frequent in order to obtain more accurate results. Raman spectroscopy, electron probe microanalysis and diffraction techniques have been reported. There are very few references of the application of XRF techniques to philately and, certainly, applications of this technique to philately in Argentina are not known.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, either on stamps, postmarks or postage stamps.  One of the most immediate analysis consists of studying the inks of the postmarks. The presence or absence of certain elements that are characteristic of inks (modern inks or inks of some predetermined period) can decide the authenticity or fake of a piece.In this work we present measurements by X ray fluorescence with spatial resolution of postmark inks of several postal pieces, some of them recognized by experts as authentic ones and others as fake ones. By means of qualitative analysis, different comparisons where performed in order to evaluate the possibilities of this technique for the detection of falsifications.The measurements were carried out using a conventional spectrometer with sample-positioning stages; microbeams were attained by  micro-collimators and also a mono-capillary.The results obtained in this work indicate that XRF with spatial resolution is a suitable technique for the authentication of postal pieces through the identification of the elements that constitute the used inks. XRF represents an excellent complement of other techniques and a significant help to the evaluation performed by experts.