This new approach can determine the relative age of the ink, in a nondestructive manner, from any two writings created at different periods of time with the same class of ink.
One of the challenges faced by the forensic document examiner is determining the age of a document/ink in order to ascertain whether entries or writings – such as those in logbooks, registers, OMR sheets, deeds, cheques, drafts, and other important documents – were executed in the same period or in different periods of time.
By Nato Locktongbam Central Forensic Science Laboratory, Directorate of Forensic Science Services, Ministry of Home Affairs, Government of India, Kolkata Dr. In order to address these challenges, an attempt was made to study the rate of diffusion of inks at different time intervals using hyperspectral imaging.
Khound Directorate of Forensic Science, Government of Assam, Guwahati Priyankar Ghosh Central Forensic Science Laboratory, Directorate of Forensic Science Services, Ministry of Home Affairs, Government of India, Kolkata Abstract The challenges faced by the forensic document examiner are to know whether entries/writings with ink made on certain documents – such as logbooks, registers, OMR sheets, cheques, drafts, promising letter/notes, deeds, wills, prescription notes, and other important documents – are executed during the same period of time, or in different periods of time, and to know whether entries/writings were executed by the same ink.
Two important aspects of these components are the ballpoint ink solvents used to dissolve or disperse the colorants, and the resins used to thicken the inks. Techniques and applications of Hyperspectral Image analysis.
The solvents evaporate with time, and the resins harden or set (by oxidation) with time.
Many attempts have been made to determine the age of ink in the last 30 years.
Different techniques have been used, based on the study of chemical and physical properties of various types of inks.
The two more commonly studied ink aging properties are: 1) how well an ink extracts into a weak solvent, and 2) how much solvent remains in the ink.
For fresh inks, both aging processes mentioned above (solvent evaporation and resin setting) contribute to each of these two properties.
No specific data bank regarding the chemical compositions and dye components for the various ink types is available.
Moreover, there are many factors affecting the rate of aging, and almost all techniques used to determine age are destructive in nature.
With relative aging, samples of two or more questioned entries (that may be on different sheets or on the same sheet) are analyzed and compared to determine which sample is older or younger than the others (Hofer, 2004).