Several postage stamps dating back to the 1890's from the Republic of Taiwan were irradiated with an external 4.0 MeV proton beam to simultaneously induce X-ray and gamma ray emission. The paper and printing inks were compared between stamps made from different dies. The elemental analysis revealed that the 4 dies of stamps were printed on only 3 different types of paper. A majority of the elements observed in the stamps were due to contributions from the paper except for the red stamps which were due to cinnabar (HgS). In addition, the elemental concentrations were different in counterfeit stamps as compared to the genuine stamps. Detailed experimental setup as well as chemical reconstructions of the pigments used in the printing inks are given.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics