KOTTAYAM: Even though ballot paper has given way to electronic voting machines, the ink applied on the left index finger of the voters has not changed. Many use the skin of the betel leaf and nail polish etc. to remove the ink, but the ink mark cannot be removed so quickly.

Finger inking started in 1962. Even after the introduction of electronic voting machines in 1999, this practice continued. The ink is manufactured by Mysore Paints and Varnishes Limited (MPVL), a public sector undertaking. Initially, ink was used only for parliamentary and assembly elections. Later it started to be used for elections in municipal and co-operative societies. Once applied to the hand, the ink dries in 40 seconds. The 'silver nitrate' present in the ink helps in drying.

Top secret

The chemical composition of the vote ink is not clear even to the Election Commission. Apart from India, MPVL's ink is used in 26 foreign countries. Many experiments have been done to find out the secret of ink that lasts for two weeks. All that was clear was that the ink contained silver nitrate. The blue ink will stick to the skin and nails for weeks, turning black as the ultraviolet rays of sunlight hit the ink. Five milliliters of ink can cover 300 people's fingers.