Examination of Gel Pen Ink by Microspectrometry

The examination of writing inks has been an integral part of questioned document examination since its inception. The types of inks and writing instruments of concern have progressed from pencil and nib pen to ballpoint and porous-point pens. The most recent development in both ink and writing instruments has been the gel-ink pen. This instrument is a marriage of the ball pen with polymeric gel ink containing both dyes and pigments as colorant and water-based gel. This paper looks at the feasibility of using a Craic Technologies Questioned Document System II (QDS II) microspectrometer as an analysis tool for the differentiation of gel-pen inks. Using several sample preparation methodologies over the full spectral range from ultraviolet to infrared, 7 different black gel inks were examined with the QDS II. Additionally, 2 blue gel inks (with common manufacture as several of the black inks) were also examined. Results of these examinations indicate the ability to differentiate, to varying degrees, the black gel inks and consistency between those inks of common manufacture (blue and black). The preferred sample preparation methodology was also identified and elucidated.