Indelible ink’s new challenger: invisible ink
- Indelible ink, the purple stain that billions of Indians show off during elections, may face an invisible challenger in the near future. The Delhi-based National Physical Laboratory (NPL), the creator of indelible ink, has a new concoction that, when applied on the finger, doesn’t leave a trace — it merely glows a bright orange when a low-intensity beam of ultraviolet light is shone on it.
- The NPL prepared the ‘invisible ink’ as part of a pilot project mooted by the Mysore Paints and Varnish Ltd. (MVPL).
- The MVPL, a Karnataka government company, has a monopoly on the manufacture of indelible ink since 1962, and is a major supplier to the Election Commission of India (ECI). It also exports the indelible ink for elections in other countries.
- The chemical — a transparent liquid — as an “organic-inorganic” mixture that was biodegradable and could be washed off in 48 hours.”
- The ink works on the principle of fluorescence — certain materials emit a characteristic glow when exposed to ultraviolet light. The NPL ink, however, glows only when exposed to a narrow band of frequencies of ultraviolet (UV) light. “Commercial UV markers or inks respond to a very broad spectrum of UV light. So, along with the ink, we’ll supply an inexpensive LED (costing no more than ₹30) that would emit a specific frequency of UV,”
