London: Researchers have shed light on the processes and materials used to forge a 75cm long Indian sword, made in the late 18th or early 19th century, which was probably used in battle.
Scientists and conservationists from Italy and the UK joined forces to study a curved single-edged sword called a shamsheer.
The sword from the Wallace Collection in London was made in India in the late eighteenth or early nineteenth century.
The design is of Persian origin, from where it spread across Asia and eventually gave rise to a family of similar weapons called scimitars being forged in various Southeast Asian countries.
Two different approaches were used to examine the shamsheer: the classical one (metallography) and a non-destructive technique (neutron diffraction).
The sword first underwent metallographic tests at the laboratories of the Wallace Collection to ascertain its composition. Samples to be viewed under the microscope were collected from already damaged sections of the weapon.
The sword was then sent to the Rutherford Appleton Laboratory in the UK. Two non-invasive neutron diffraction techniques not damaging to artifacts were used to further shed light on the processes and materials behind its forging.
"Ancient objects are scarce, and the most interesting ones are usually in an excellent state of conservation," said Eliza Barzagli, from the Institute for Complex Systems and the University of Florence in Italy, who led the study.
"Because it is unthinkable to apply techniques with a destructive approach, neutron diffraction techniques provide an ideal solution to characterise archaeological specimens made from metal when we cannot or do not want to sample the object," said Barzagli.
The research established that the steel used is quite pure. The high carbon content of at least one per cent shows it is made of wootz steel. This type of crucible steel was historically used in India and Central Asia to make high-quality swords and other prestige objects.
Its band-like pattern is caused when a mixture of iron and carbon crystallises into cementite. This forms when craftsmen allow cast pieces of metal (called ingots) to cool down very slowly, before being forged carefully at low temperatures.
Barzagli's team believes that the craftsman of this particular sword allowed the blade to cool in the air, rather than plunging it into a liquid of some sort.
Results explaining the item's composition also lead the researchers to presume that the particular sword was probably used in battle.
Craftsmen often enhanced the characteristic "watered silk" pattern of wootz steel by doing micro-etching on the surface.
Barzagli said that through overcleaning some of these original 'watered' surfaces have since been obscured, or removed entirely.
The study is published in Springer's journal Applied Physics A - Materials Science & Processing.