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CSIR’s Memorable Mark with Indelible Ink

21 Oct 2016


Come elections and a deep purple mark on the voters’ left forefinger is a familiar sight. What most of us are, however, not so familiar with is the fact that this inerasable ink mark is a gift of CSIR to the Nation. Once applied, this mark indicates that the voter has cast his/her vote, and thus, prevents that person to vote a second time. Thanks to CSIR scientists working in the National Physical laboratory (CSIR -NPL) New Delhi, for their painstaking efforts that led to devising the chemical formula of indelible ink.

One of the earliest achievements of CSIR, it was to counter the challenge of fraudulent voting that the research work on formulating indelible ink was initiated in 1950’s by scientists in the erstwhile Chemical Division and later patented by the National Research Development Corporation (NRDC), New Delhi.

The Mysore Paints & Varnish Ltd., a Karnataka Govt. Undertaking, has been licensed to manufacture the ink. This more than seven decade old Company entered the business of making indelible ink in 1962. Today lakhs of 10 ml bottles are supplied to the State administration.

It is matter of pride that today this innovation of CSIR is going places, asthe indelible ink is exported to more than 25 countries that include Canada, Ghana, Nigeria, Mongolia, Malaysia, Nepal, South Africa and the Maldives. However, as different countries follow a different mode for applying the ink, the Company supplies the ink as per customer specifications. For example, in Cambodia and the Maldives, voters need to dip his/her finger into the ink while in Burkina Faso the ink is applied with a brush, and nozzles are used or its use in Turkey.

As the ink is photo-sensitive, it needs to be protected from exposure to direct sun rays. Therefore, amber-coloured plastic containers are must for storing the ink, which in earlier times was stored in brown-coloured glass bottles. On application, the ink remains on the fingernail for at least two days, to even up to a month depending upon the person’s body temperature and the environment. The ink contains silver nitrate, which on reaction with the nail and on exposure to light gets darker.

This water-base ink also contains a solvent like alcohol to allow its faster drying, besides having some dyes. The composition of indelible ink is optimized such that it diffuses into the skin spontaneously to give a definite marking which is resistant to chemical and mechanical manipulations.The precise protocol for making this ink including its chemical composition and the quantity of each constituent is, however, not known to many people.

The formulation of indelible ink, based on an age-old process, is truly innovative for the original formula has stood the test of time.

{This Feature has been received from CSIR (Unit for Science Dissemination), Ministry of Science & Technology, New Delhi}.

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