Stainless iron: what is the secret of India's world-famous 'wishing pillar' and what this 1,600-year-old column look like

In India, inside the Qutb Minar New Delhi complex, visitors immediately notice a 7.2-meter, six-ton iron column with a decorative top, which is even older than the complex. However, it is not the column itself that is surprising but its appearance.

The column, which is now 1600 years old, looks the same as the day it was forged. Its appearance is unaffected by age or the environment, including the high temperature in the Indian capital and increasing pollution, CNN writes.

How does it resist corrosion for so long?

Generally, structures made of iron and iron alloys that are exposed to air or moisture oxidize over time, causing them to rust, unless they are covered with layers of special paint, like the Eiffel Tower. Scientists both in India and abroad began studying the iron pillar in Delhi in 1912 to try to figure out why it had not corroded. It wasn't until 2003 that experts from the Indian Institute of Technology (IIT) in the northern city of Kanpur solved the mystery by revealing the answer in the journal Current Science.

The experts found out that the column is mostly made of wrought iron, has a high phosphorus content (about 1%) and does not contain sulfur and magnesium, unlike modern iron. In addition, ancient craftsmen used a technique called "forging welding".

This means that they heated and forged the iron while maintaining a high phosphorus content, an unusual method for modern practice.

"A thin layer of 'misavit,' a compound of iron, oxygen, and hydrogen, was also found on the surface of the column. This layer is formed catalytically due to the high phosphorus content in iron and the absence of lime, which further increases the durability of the column," archaeo-metallurgy expert R. Balasubramaniam commented.

The scientist praised the metallurgists for their ingenuity, describing the column as "a living testament to India's ancient metallurgical skills."

Its durability is attested to by historical accounts, including an incident in the 18th century when a cannonball fired at the column reportedly failed to break it, demonstrating the exceptional strength of this ancient monument.

Today, the pillar serves as the emblem of scientific organizations such as the National Metallurgical Laboratory and the Indian Institute of Metals.

Cultural significance and preservation efforts

According to one legend, if you stand with your back to the pillar and embrace it with your arms, making sure your fingers touch each other, your wish will come true. This is a tradition that endows the pillar with a spiritual significance that exceeds its historical value.

However, the ASI (Archaeological Survey of India) has placed a fence around the pillar to minimize human impact. Conservation architect and cultural heritage expert Pragya Nagar believes that the pillar has been perfectly preserved within the complex despite the demolition and reconstruction around it over the years.

"If we do look at the technique that was used to create the column from a new perspective, beyond simply recognizing its ancient origins, we may discover ways to use similar techniques to develop sustainable alternative materials, given the environmental damage associated with processes such as metal mining. It is crucial to look at history not only as relics and monuments to be preserved and marveled at but also as a repository of traditional knowledge and local practices. This holistic approach can pave the way for a more sustainable future," she commented.

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