A novel, non-invasive, multi-purpose and comprehensive method to date inks in real handwritten documents based on the monitoring of the dye ageing processes

Simple and Cost-Efficient Classification of Ballpoint Pen Inks Using Digital Color Analysis

“…Similar trends were observed as a result of the more formalized chemometric processing (hierarchical cluster analysis, see more in ref ) of the obtained fitting parameters (Figure A).…”

Classification of ballpoint pen inks based on selective extraction and subsequent digital color and cluster analyses

“…2A and B indicates the need for external influence to distinguish the ink of blue ballpoint pens. It is possible to obtain five separate clusters using the difference between the average values of RGB prior to and after extraction: [1 + 9 + 12 + 13], [2], [3 + 5 + 7 + 10 + 14 + 15 + 16], [4 + 6 + 8] and [11]. These results are in adequate agreement with the visual perception of the ink colors (see Fig.…”

“…The values of color components were averaged over all the pixels of each stroke. Two different approaches were used to reveal the optimal analytical signal: (1) absolute average values of color components (X w = R w , G w , B w ), or (2) the difference between the average values of R w , G w , B w before and after extraction:…”

“…S1. † We can see that the replicate strokes of the same pens entirely belong to the original five clusters: [1 + 9 + 13], [2], [5 + 7], [6 + 8], [11]. 4), (7).…”

“…The latter prompts the search for new, more efficient, and less time-consuming approaches to the examination of handwritten artifacts. Various instrumental methods are currently available for the analysis of dyes and pigments: IR spectroscopy, UV/vis spectroscopy, 2 Raman spectroscopy, [3][4][5][6][7][8] thin layer chromatography (TLC), [9][10][11] capillary electrophoresis, 12 high-performance liquid chromatography (HPLC); 13,14 as well as for the analysis of solvents utilized in ink formulations, e.g. gas chromatography (GC).…”