The Romans imported their best steel from the East, not in the form of blades, but in cakes of steely iron (later known as wootz) manufactured in the Hyderabad region of India. The earliest known examples of this date from about the 6th century BC, and by the 1st c. AD Indian smiths were very skilled in its manipulation. It reached the Romans through Abyssinia, and was generally believed to come from China, as the real place of its origin seems to have been kept a trade secret. The Romans knew it as Seric Iron. Parthian steel, made in Persia by a somewhat similar method, was also highly valued and widely exported.
The Indian method was to heat black magnetite ore in the presence of carbon in a sealed clay crucible inside a charcoal furnance. An alternative to this was to smelt the ore first to give wrought iron, which was heated and hammered to free it from slag and broken up into small pieces, while the Persians generally used iron bars, heated with charcoal or plumbago. The carbon was obtained by the Indian smiths from bamboo and the leaves of certain plants, and the crucible was piled up with a number of others and heated in a furnance in a blast of air for about two-and-a-half hours. THe ore was reduced to iron, which then began to absorb carbon; when it had absorbed 3 or 4 per cent., the melting-point was lowered sufficiently for the iron to melt, just as the addition of salt lowers the melting-point of ice. The molten iron was heated and cooled again four or five times, and according to others was left in the furnance and allowed to cool down with it very slowly over a period of days. At the end of the process a round cake of metal was obtained, about 5 inches in diameter and 2 lb. in weight, sufficient for two sword-blades. Although with such a high carbon content one would expect the metal to be equivalent to cast iron, very hard and brittle, the slow cooling caused chemical and physical change to occur in the form of the carbon present, and it was possible to work the iron so as to produce weapons of excellent steely quality. The 'wootz' was usually marketed in circular form, or in short, stout bars.
Eastern steel was much valued by European smiths in Roman times. It was not easy to forge, but a skilled smith working with extreme care could avoid cracking in the initial forging process, since the brittle material was no longer in continuous planes of weakeness (as in cast iron) but dispersed in tiny dots. It was the working of this discontinuous material which produced the charateristic watered pattern running over the whole surface of damask sword-blades, giving the appearance of watered silk or moiré ribbon. As a result of forging, the material lost the tendency to crack and became tough and steely, and successful working produced weapons of extreme flexibility and great hardness, which would take a perfect cutting edge. Methods of working varied: one was by flowing the metal in two or more directions by hammer blows, followed by prolonged annealing and quenching, while another was to work the steel at dark red heat without quenching. The carbon content of good damascened blades was usually between 0.7 and 1.5 per cent., so there was evidently considerable loss of carbon during the forging process.
The pattern on the blade was brought out by polishing and etching, and this also necessitated long and careful work. A mineral called zag was used in solution, which Smith believse to have been a natural ferric sulphate.
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