Different types of inks having certain medicolegal importance: Deciphering the faded and physically erased handwriting

Abstract

Disappearing ink is a type of ink which could be used to forge documents as it will fade away without any trace within 40–65h. Erasable ink is another type of ink easily removed by certain rubbers incorporated in each pen. Both types of inks were applied separately on different types of papers (checks, standard white foolscap, and plain white A4 paper). For vanishing ink, it was observed visually in the first 6h and then every 6h. It was found that the vanishing ink disappeared completely within 2h on checks, 36h on standard white foolscap paper, and 40h on plain white A4 paper. For erasable ink, the written strokes were manipulated manually using the incorporated eraser. Deciphering the faded writing failed by the conventional methods, but oblique light can reveal the indentation marks. The faded writing became visible when treated with weak alkaline (NaOH) solutions. Erasable ink was deciphered with the aid of infra-red radiation combined with VSC-6000 as clear white traces against red fluorescence. It was concluded that the use of a weak (NaOH) solution is an effective method for revealing the faded writing, and the infra-red illumination is also effective.