Super Steel Super

PADMA RAO

India’s Wootz steel and indigo dye are testament to the high level of Super Steel scientific and technological & knowledge that India possessed through the Feature Article Feature Super Dye ages.

the handiwork of specialized artisans cooling. The blade smiths skillfully made called Kammaras of South India. It was use of these patterns in the material by URING the Crusades, the Christian made in the iron ore belt of Karnataka, manipulating the angle of the blades, and warriors encountered Muslim Andhra and Tamil Nadu, ranging from the polishing the blade. The final product had Dsoldiers, who had better weapons. southern tip of India to Vidarbha. Golkonda, grey patterns on a black background, The weapons were made of a harder steel Bhadravati in Karnataka and the making it a thing of beauty. The more with a sharper cutting edge known as megalithic site of Kodumanal in Tamil famous patterns were the rose pattern and Damascus steel. Nadu. the ladder pattern. Tipu Sultan’s famous In his famous book, The Talisman, 19th The name Wootz is a corruption of blades had the bubris tiger stripe pattern century British writer Sir Walter Scott the Kannada word ‘Ukku’, which means ingrained in them. describes the weapons of Sultan Saladin steel. In Tamil, it is called ‘Irku’. The steel Medieval observers have written of the Saracens. His description of Saladin’s was prized so much in the West, that about the production of Wootz steel, fearful scimitar as opposed to the English Alexander the Great is said to have carried which was made using the crucible broadsword wielded by Richard the some Indian steel swords on his return from process. Iron ore was fed into clay Lionheart is graphic. The scimitar was India. Herodotus, Tsesius and other Greek crucibles, making of which was a made of Damascus steel, with “a curved philosophers have expressed their specialized skill. The ore was melted and and narrow blade, which glittered not like admiration for the Indian steel. The steel wrought iron was separated from the slag. the swords of the Franks, but was, on the ingots were exported to the Middle East To the iron, a measured quantity of carbon contrary, of a dull blue colour, marked and they were forged again in Damascus in the form of charcoal or wood pieces with ten millions of meandering lines...” Little to make daggers and swords. was added, and the charge heated to did Scott know that the famed Damascus By the turn of the 18th century, tens of high temperature in tightly covered steel encountered by the ancient thousands of tons of the steel buttons were crucibles. A batch of covered crucibles crusaders was forged from the specialty exported to Damascus from the were placed in a furnace and fired for 14 Wootz steel of South India. Coromandel coast and from Malabar. to 24 hours at temperatures of round 650 Wootz steel was developed in India There is evidence that Jewish traders of to 7500 C. The fire was regulated using hundreds of years before the Christian era. South India shipped ingots of Wootz steel buffalo hide bellows. Then the lid was Ancient Indian manuscripts mention steel to Syria in the 12th century. removed from the crucible and the slag razors, surgical instruments, stone cutting Wootz steel is synonymous with was poured out. The steel was formed in instruments and files made of steel. A Damascus steel. ‘Damas’ means water in the form of ‘buttons.’ chisel with a hardened point, found in Sri Arabic, and the watered pattern on the Swords were made by forging the Lanka, dates back to 500 B.C. The 12th blade inspired the name. The daggers and steel and quenching it. The blade had to century Arab scholar Edrissi has scimitars made of Damascus steel were be quenched rapidly to make it strong. commented, “The Hindus excelled in the prized all over the world because of their Indian blacksmiths quenched the red-hot manufacture of iron, and it is impossible strength that enabled them to cut through blade by plunging it into a banana plant to find anything to surpass the edge from any other blade. They had such incredible and cooling it overnight. The ancient Indian Hindustani steel.” flexibility that they could bend 90 degrees scientist Varahamihira has written that the In the West, metallurgists discovered without breaking. sword should be quenched with a solution the importance of adding carbon to iron The blades made of Wootz Damascus of banana plant ashes. to make it hard only in the 19th century, by steel typically have a beautiful pattern in In order to get the desired quality of which date the process for producing the material itself. This is because of the steel, the Kammaras had to take the hard, tool steel was already centuries old presence of the carbide molecules in the greatest care while selecting the raw in India. The strong, high carbon steel was matrix of the material produced during materials. It had to be poured out at the SCIENCE REPORTER, AUGUST 2011 16 Feature Article Wootz steel was developed in India hundreds of years before the Christian era. Ancient Indian manuscripts mention steel razors, surgical instruments, stone cutting instruments and files made of steel.

exact time, or the steel would be useless. steel, and the handles were decorated Interest about this high quality steel The clay crucible had to be made with rubies and emeralds. The legendary has revived in recent times, but all efforts perfectly. The wood or charcoal used had sword of Tipu Sultan, which brought fear to produce it have been in vain. Although to be from specific trees. It is known that into the hearts of the British troops, was it was not studied in the early part of the the wood of the Tanner’s Cassia or forged in Bednur in India. Tipu Sultan had 20th century, in the later half of the century, Thangadi tree Cassia aurantifolia was used many weapons made of Wootz steel. The Oleg Sherby and Jeff Wadsworth in the production of the highest quality blades were decorated with the bubris conclusively proved that the material Wootz steel. tiger stripes design, while the gold handles exhibited superplasticity. Superplastic There is a record of a highly skilled were inlaid with precious stones. The light materials are in high demand as they can blade smith in Tanjore. The swords of the coloured tiger stripes on the black be fashioned into complex shapes. Mughal princes were made of the famous background of the blades are at once Scientists including J.D. Verhoeven, A. beautiful and intimidating. Pendray, S. Srinivasan and Sharada The manufacturing units of the steel Srinivasan have done commendable were mainly in Mysore, Tanjore and research on Wootz steel. J.D. Verhoeven Golkonda, but unfortunately none of them showed that the presence of small survive today. There is evidence of crucible quantities of Vanadium was the cause of steel production centres in the megalithic the patterns created by the carbide site of Kodumanal. In places like Lahore, particles. There is a belief that when the Rampur and Allahabad, fine knives and iron ore that contained minute quantities daggers were fashioned from this steel of vanadium became exhausted, Wootz during the Sepoy Mutiny of 1857. After the steel production also stopped. The Mutiny was quelled, the British confiscated blacksmiths of ancient India took away the and destroyed hundreds of weapons. secret of making the super steel with them. Although Wootz steel excited the imagination of the scientists of the 18th and Indigo for 19th centuries, none could duplicate it. Independence Such greats as Michael Faraday were Indian Talwar The Panchatantra, the Indian collection of fascinated by this patterned steel from fables dating back to the India. He attributed the high strength, third century BC, has a story of a jackal ductility and beauty of the steel to the that falls into a vat of blue dye and is turned presence of silica and alumina, which is permanently blue. He then pretends found to be erroneous. It has been found that he is a superior animal and bosses that that true Damascus steel has the etched crystalline structure due to the over his companions. There are other presence 1.3 to 1.5% carbon. mentions of the ‘Blue Vat’ in ancient Sanskrit Arab scholar Edrissi has Incredibly, Wootz steel disappeared texts. commented, “The Hindus from the market after 1860, and the Indigo dye was known to the Indians excelled in the process of manufacturing it was lost since more than five thousand years. It is manufacture of iron, and forever. Benjamin Huntsman of Sheffield one of the oldest dyes made by man. it is impossible to find who is credited with the invention of the Besides the Indians, it was known to the anything to surpass the modern crucible method of steel making ancient Egyptians and the Phoenicians. edge from Hindustani in 1750, most likely got his inspiration from Indigo dyeing was one of the earliest steel.” the processes described by the European specialty professions of the world. The travelers in India. indigo dyers in India were a highly 17 SCIENCE REPORTER, AUGUST 2011 Feature Article

Dye in vats Denim dye

Indigo dye was known to the Indians since more than five thousand years. It is one of the Indigofera oldest dyes made by man. Besides the Indians, it was known to the ancient Egyptians and the Phoenicians. respected class of people. There is presence of an alkali, it can be made to in Europe during the time of the Industrial evidence that indigo was used during the colour the fabric. In an Indigo dye vat, the Revolution, and this led the entrepreneurs Mauryan period. dye is in solution in an alkaline medium. of the time to acquire large plantations of The ingenuity of the ancient Indian The fabric to be dyed is immersed in the indigo in India and the West Indies. artisans who had perfected the technique greenish yellow solution in the vat and taken It is hard to believe that this common of manufacturing a precious dye from a out. As soon as the indigo molecules come wild plant inspired one of the earliest non- common plant and finding ingenious ways in contact with the oxygen in the air, violent movements by the people. Many of using the dye on cotton and silk fabric is oxidation takes place, and they change of the British petty officers of the East India something to be proud of. colour to a deep blue. The oxidation traps Company bought up land in Bengal and The indigo plant Indigofera tinctoria is the molecules in the matrix of the fabric to Bihar after their retirement, and started an insignificant, small, wild herb or shrub give it a deep indigo colour. The process is growing indigo. The planters exploited the that is found in disused fields and vacant fascinating to watch. local farmers of Bengal and amassed plots all over India. However, this plant was The dye has a long history of usage. great wealth in the 18th and 19th centuries. the source of ‘Blue Gold’, as the indigo The Romans and the Greeks prized the dye The farmers were forced to cultivate dye was known in the Middle Ages. that was imported from India. The name indigo plants instead of food crops. They Although there are nearly 700 varieties Indigo is from the Greek word Indikon, were given loans at exorbitant rates of of the Indigo plant, it is the Indigofera meaning ‘Blue dye from India’. In the Middle interest by the planters, so that the farmer tinctoria that gives the largest amount of Ages, silk from China was dyed by indigo, remained in bondage till his death, and his family after his death. the dye. All the indigo dye now produced and so indigo came to be associated with The inhuman conditions made the is synthetic, but until early 1900s it was luxury goods from the Orient. farmers revolt against the planters. Farmers produced using the leaves of the In Japan, indigo was put in a vat where belonging to all communities joined in the Indigofera tinctoria plant. a culture of special anaerobic bacteria revolt. The farmer Haji Mulla said that he To obtain the dye, the indigo plants was maintained. The vat was kept warm at would rather beg than plant indigo in his are cut and steeped in water for 12 hours all times, and the fabric was dipped into farm. When the Biswas brothers took up in vats. The extract, which is a greenish the indigo solution in the vat. Japanese tie arms against the planters, the revolt spread colour, is again poured into vats and and die Shibori and Kasuri were made like wildfire. It was quickly suppressed by fermented. The fermented liquid is stirred using this technique. The summer kimonos the government and the leaders of the vigorously to bring it into contact with of the Japanese, which were made of revolt were executed. oxygen. An insoluble precipitate forms, cotton, were dyed using indigo. In But the Indigo Revolt sowed the seeds which is collected and pressed into cubes. America, indigo plantations were of a desire for independence and was Since this process uses vats, it is known as a established in Carolina, and slaves were the precursor to the non-violent vat process. This process is very labour made to work in them. The indigo dye is still Satyagraha movement that brought intensive and expensive, but, on the other used to colour the blue jeans that are independence finally to India. hand, toxic wastes released by this process popular among all sections of people. are minimal compared to the waste Until Vasco da Gama discovered the released by the synthetic manufacture of sea route to India, spices and indigo were Ms Padma Rao teaches Physics and Mathematics indigo. meant only for the royalty and nobility in at the National Hill View Public School, Bangalore. Since natural indigo dye was insoluble Europe. After the discovery of the sea route Address: 69, 12th Main, Ideal Homes Township, in water, it did not stick to the fabric as to India, indigo became a much sought Raja Rajeshwari Nagar, Bangalore-560098; Email: most dyestuffs did, and it was a challenge after commodity in the West. It became [email protected]; Blog: http:// to the dyers. But by reducing it in the the most expensive and fashionable dye indianflowersandherbs.blogspot.com SCIENCE REPORTER, AUGUST 2011 18