The iron pillar that won’t rust

 Sunday Tribune, April 19, 2009  

 T. Simharajan on this hand-forged block of iron from India’s past that continues to remain rust-free even 16 centuries after its making

For the last 1600 years, the rustless wonder called the Iron Pillar of India, near the Qutub Minar at Mehrauli in Delhi, continues to baffle contemporary scientists, who cannot determine the method of manufacture, which prevented the iron from rusting for these last 16 centuries. 

The pillar, made up of nearly seven tones of 98 per cent wrought iron of pure quality, is 7.21m (23 feet 8 inches) high, with 93 cm buried below the present floor level, and has a diameter of 41cm (16 inches). The pillar has been brought here evidently from somewhere, else, as no other relics of the fourth century are found at the site. There is a strong local tradition that it was brought here by Anangpal, the Tomar king who is credited with the founding of Delhi in 1020 A.D.

According to the inscription on it, the pillar was erected at its original venue by Chandragupta II Vikramaditya (375–414 C.E.) and according to archaeologists, originally the column with a l of Chakra (discus of God Vishnu) at the top, was originally located at a place called Vishnupadagiri (meaning “hill with footprint of Lord Vishnu”). This location has been identified as modern Udayagiri, a town located about 50 km east of Bhopal, in central India. Vishnupadagiri is located on the Tropic of Cancer and, therefore, was a centre of astronomical studies during the Gupta period. The Iron Pillar served as a sundial, when it was originally at Vishnupadagiri. The early morning shadow of the Iron Pillar fell in the direction of the foot of the God Vishnu in one of the panels at Udayagiri only around the summer solstice on June 21. This pillar was plundered by Islamic hordes from a Vishnu or Jain temple nearby and added as a trophy in the Quwwat al-Islam mosque which was built in 1193 A.D at Delhi by Qutubuddin Aibek the founder of the Slave Dynasty at Delhi.

It did not attract the attention of scientists, till the second quarter of the 19th century. The first reports of the pillar were by British soldiers, and one of them Captain Archer talked about an inscription of unknown antiquity on the pillar, which nobody could read. Later, James Prinsep, a British archaeologist deciphered the inscription in 1838 and translated it into English in the journal of the Asiatic Society of Bengal. The inscription referred to a ruler named Chandra, who had conquered the Vangas and Vahlikas, and the breeze of whose valour still perfumed the southern ocean. Historians opine that the king who answers the description is none but Samudragupta, the real founder of the Gupta Empire in (375–414 AD).

The existence of this pillar, so ancient without any trace of rust, excited curiosity of the scientific world and many attempts have been made to find out its composition. In 1961, the pillar was dug out for chemical treatment and preservation and reinstalled by embedding the underground part in a masonry pedestal. Chemical analyses, then, indicated that the pillar was astonishingly pure or low in carbon compared with modern commercial iron.

In 1963, M. K. Ghosh of the National Metallurgical Laboratory concluded that the pillar had been very effectively forge-welded. B. B. Lal, chief chemist at the Archaeological Survey of India, also came to the conclusion that the pillar was not cast, but fabricated by forging and hammer-welding lumps of hot pasty iron, weighing 20 to 30 kg, in a step-by-step process. The surface of the pillar retains marks of hammer bows. It is assumed that 120 labourers took a fortnight to complete this daunting task.

In 2002, metallurgists at Kanpur, IIT, headed by Dr. R. Balasubramaniam, have come to the conclusion that a thin layer of “misawite”, a compound of iron, oxygen and hydrogen, has protected the cast iron pillar from rust. According to them, the protective film took form within three years after erection of the pillar and has been growing ever so slowly since then. After 1,600 years, the film has grown just one-twentieth of a millimetre thick.

A fence was erected around the pillar in 1997, because visitors were damaging the treasure. There is a popular tradition, that it was considered good luck, if you could stand with your back to the pillar and make your hands meet behind it.

Mystery or not, the Delhi Iron Pillar serves as a guidepost for metallurgists in the 21st century. It is a classical example of massive production of high-class iron and is the biggest hand-forged block of iron from our antiquity. It is a demonstration of the high degree of accomplishment in the art of steel making by ancient Indian steel makers. It has been claimed that the Indians were the only non-European people who manufactured heavy forged pieces of steel and the pieces were of the size that the European smiths did not learn to make more than 1000 years later. Even with today’s scientific advances, in the 21st century only four foundries in the world could make such a large pillar and none would be able to keep it rust-free.