Prepared Disappearing Ink and Deciphering of Documents

Abstract

Disappearing inks can be used for forgeries in many fields. In this study, thymolphthalein indicator solution was prepared as a disappearing ink. A total of 54 different solutions containing thymolphthalein were prepared at six different concentrations and nine different pH values. Among the prepared solutions, 0.16 g/50 mL and 0.32 g/65 mL thymolphthalein at pH 14 were the optimum solutions that were not distinguishable from regular ink when applied to promissory note. Fountain pens were filled with the abovementioned ink solutions and applied to promissory notes for experimental purposes. After 40 h, ink residues were not visible on promissory notes written with the ink with the optimum pH (pH = 14) value. To decipher the entries that disappeared, an instrumental method (Video Spectral Comparator‐8000) and a chemical method (using NH3 vapor) were used, succeeded at 0.32 g/65 mL, but failed at 0.16 g/50 mL thymolphthalein. Therefore, NH3 had to be sprayed for 0.16 g/50 mL with negligible harm.

Interpol questioned documents review 2019–2022

“…Asicioglu et al [ 395 ] prepared disappearing inks to analyze the effects of thymolphthalein concentration and pH of the ink solution on the disappearance time and on decipherment. The authors used both a video spectral comparator (254 nm illumination) and a chemical method (NH3 vapor) to decipher the disappeared text.…”

A Review of Documentation: A Cross-Disciplinary Perspective

“…The new ways of internet-based communications and tools have expedited and modernized how documents are generated, authenticated, shared and analysed. Unfortunately, in another spectrum, the internet has facilitated and increased access to methods and ideas relating to forgery [68], crime, and terrorist acts.…”