The Science of voter’s ink used in the election

The purple coloured ink popularly known as voter’s ink applied on the left-hand index finger of the voter in the general elections contains Silver nitrate as the main constituent. Silver nitrate stains the skin on exposure to ultraviolet light. The ink dries out in less than 40 seconds. Once applied, ink cannot be removed by washing with soaps or detergents or by applying any chemical. The dark stain remains for several days without harming the skin.

It can only fade over time. In the year 1962, the ECI (Election Commission of India) in collaboration with the union law ministry, The National Physical Laboratory (NPL) and NRDC (National Research Development Corporation) made an agreement with Mysore Paints and Varnish Limited, for supplying this ink for the parliament, assembly and other general elections to all the states in India to prevent the election fraud. This water-based ink also contains a solvent like alcohol to allow its faster drying and some dyes.