Physical Distinguishable of Heterogeneous Overlapping Resulting from Stamp-pad and Laser Printing Inks

Document Type : Original Article

Authors

1 Egyptian Petroleum Research Institute (EPRI), Nasr City, Cairo, Egypt

2 Al-Azhar University, Chemistry Department, Nasr City, Cairo, Egypt

3 Forgery & Counterfeiting Department, Forensic Medicine Authority, Cairo, Egypt

Abstract

Detecting the arrangement of intersecting stamp-pad ink and toner laser printing strokes is an excellent method of examining the documents originality. In this study, different six brands of stamp-pad inks, five laser printers of various brand and model, three types of paper surface, two kinds of seal materials and three methods of seal manufactures were utilized to produce the samples of heterogeneous intersecting strokes. A combination of the microscopic method as a digital microscope and analytical instrumental technique as Raman spectroscopy were performed to determine the arrangement of intersecting strokes. The digital microscope succeeds in detection the arrangement of intersecting strokes of some stamp-pad ink and fails in detection the others depending on their brands and colors through notation four physical properties at intersection point the specular reflection, the ink and toner gloss, gaps and spreading. The Raman spectroscopy determined the ink or toner stamped or printed later by comparison the spectra of pure ink, toner and their intersections and succeeds in detection all samples through the spectral data such as peak location and peak intensity. The combination of a digital microscope and Raman spectroscopy which applied here successfully discriminates the arrangement of intersecting strokes of toner and all brands of stamp-pad inks regardless of their brands and color.

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History

  • Receive Date: 16 January 2019
  • Revise Date: 15 March 2019
  • Accept Date: 18 March 2019

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