A study related to Dot-matrix printers has been carried out in order to analyze the effect of change of substrate on its printing characteristics. Twenty Dot-matrix printers and five types of substrates or white pages have been selected for the study. The printouts have been taken on all the five types of white papers from each of the twenty Dot-matrix printers. These printouts have been examined using stereomicroscope 4x40magnification and VSC 2000 C to examine the features such as change in colour of ink, lustre of printing text, impact of printing, spreading of ink, background noise, UV fluorescence and absorption spectra. It has been concluded that the physical characteristics of dot-matrix printing gets changed by changing the type of substrate even in case of the same printer. Thus, the results of this study would definitely help the forensic document examiners to give an accurate opinion on the cases related to Dot-matrix printouts, specifically in the examination of multiple documents consisting of different types of papers.

On the basis of the type of ink, pen inks are classified as ballpoint pens or non-ballpoint pens. Ballpoint pen inks are oil-based inks (ballpoint pens). While non-ballpoint pen inks are water-based inks (gel pens, fountain pens, pilot pens, fibre tip pens, etc.). Different approaches related to the determination of the age of ink were proposed in the literature, including ballpoint pen inks, non-ballpoint pen inks and stamp pad inks. This study provides a comprehensive appreciation of analytical research studies that were published from the year 2000 to year 2020 on the determination of the age of inks. Owing to contemporary technological advancements, the process has been developed in many folds. However, its reliability is questioned due to the variability in methods and results. Research works related to the aging of ink have been compiled to assist the researchers and the forensic document examiners and to provide an overall insight regarding the works done so far. In an attempt to unravel this issue of questioned document examination, a critical and systematic review of the literature is proposed to encourage the usage of various tools and techniques necessary to establish the age of ink in different case works.