Library Dissertation Showcase

The influence of external factors on the aging of ink for forensic purposes

  • Year of Publication:
  • 2022

Forensic ink analysts often date ink entries to determine if the ink is older than it is claimed to be. One method to make ink appear older is to artificially age it via heat. However, artificial aging is still seen as a controversial topic. Lots of studies into artificially aging inks over days and weeks has been carried out, yet very little research has been conducted into artificial aging over periods of hours. Hence, this research is necessary. In this study, four coloured ballpoint pen ink samples were heated at three temperatures (50, 75 and 100°C) for three different time periods (2, 4 and 6 hours) to examine the affect that time and temperature have on the ink aging process. It was hypothesised that as time and temperature increased, the ink samples would age more (i.e. show greater signs of aging). Three analytical techniques were used to examine the ink: colourimetry, Video Spectral Comparator and Fourier Transform Infrared spectroscopy. Differences in ink colour, noted with colourimetry, occurred as time and temperature increased. However, these differences were not significantly different. Under VSC filters, it was noted that samples which had been heated for longer at higher temperatures appeared duller due to the degradation of dyes as part of the ink aging process, which supports the hypothesis. Using FTIR, it was determined that some signals, such as an absorbance band at 870 cm-1, are associated with the ink sample aging. This 870 cm-1 band, which was linked to the degradation of dyes as inks age, decreased at higher temperatures and after longer time periods, supporting the hypothesis that inks age as time and temperature are increased. FTIR also noted that increasing the temperature effected the aging process more so than increasing the time of heating. Overall, the results support the hypothesis of this study: increasing time and temperature does age ink more, with the temperature ink is heated at playing more of a role in the aging process than the time it is heated for.

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