Ink analysis is an important part of forensic document examination, enabling identification of alterations and their source. There are two main types of technique used in the analysis of ink, destructive and non-destructive. Raman spectroscopy is a non-destructive technique which is becoming more popular for use in ink analysis, whilst the VSC’s potential is still being explored.
This study used Raman spectroscopy in combination with the video spectral comparator (VSC) to examine similarities and differences between seven pen types (ballpoint, rollerball, fine liner, felt tip, fibre tip, gel and fountain) in four colours (black, blue, green and red). The results were used to determine whether the pen types in each colour category could be distinguished. Within this study, two paper types were compared to determine whether they affected the two examination techniques, and what the affect was. Some samples were also left to age for two weeks to see if having a longer curation period impacted the Raman spectra or VSC results. Finally, two sets of samples on each paper type were wet with either deionised or tap water to evaluate this impact on pen type discrimination.
Black ink pens were most discriminatory, whilst red ink pens showed the most commonalities, thus were indistinguishable. The two paper types were found to have the same level of impact on the results however, the level of impact was not determined. The ageing had little impact on the ink analysis, the only difference being that the aged black ink did not fluoresce under spotlight, whilst the fresh sample did. The wet samples also did not have a significant difference in results. The study found that Raman analysis used with the VSC was not sufficient to completely discriminate between pen types.
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