As the Lok Sabha elections progress, voters across the country are receiving a drop of blue ink on their left finger after casting their votes. This ink, used to prevent duplicate voting, is a product of Mysore Paint and Varnish Limited, and it comes with an interesting cost and chemical composition.

Developed by scientists of the Council of Scientific and Industrial Research at the National Physical Laboratory in 1952, the ink formula was later patented by the National Research Development Corporation. Currently, one bottle of this ink, containing 10 ml, costs Rs 127, making the price of one drop approximately Rs 12.70. A one-liter bottle, priced at Rs 12,700, can mark up to 700 fingers.

Despite its small price, this ink is not available for retail purchase. It can only be procured by government or election-related agencies. Since 1962, Mysore Paint and Varnish Limited has been the sole authorized supplier of this ink in India under a special license granted by the National Research Development Corporation, in agreement with the Election Commission, the Union Law Ministry, and the National Physical Laboratory.

The ink's composition includes silver nitrate, which reacts with the salt in the body to form silver chloride, turning black on contact. This reaction is irreversible and cannot be washed off with water or soap. Additionally, the ink dries in less than 40 seconds due to its alcohol content.

This ink, first used during the 1962 Lok Sabha elections, is not limited to India; it is also supplied to more than 25 countries, including Canada, Ghana, Nigeria, Mongolia, Malaysia, Nepal, South Africa, and Maldives.