In 1842, John Hershel, fascinated by photography, sought to discover the effulgence of colour in photographs. He observed iron salts react to light and used the experiment to invent the process of cyanotype printing. He witnessed photographs change to shades of blue. In a similar quest, Anna Atkins, Hershel’s friend’s botanist daughter, used dried seaweeds on paper, inspired by Hershel’s experiment, and became one of the earliest users of cyanotype, publishing her work in a three-volume-compilation, Photographs of British Algae: Cyanotype Impressions in 1843. With the rise in digitisation, this phenomenon seems to have re-emerged. It offers an alternative to the processes of photographic printmaking.

The enigma excited artist and photographer Urna Sinha when she learnt about it in Shantiniketan, for the first time, during her undergraduate studies in art. “I was amazed by what time, light, and water could do to our images,” she shares.