| Abstract: |
Bidri ware is a well-known class of inlaid metalwork used to make such items as decorative jugs, huqqas and other containers, produced in India from the 17th century or earlier and which is still being made today. The early history of bidri ware is not certain though the class as a whole is well studied and published, for example by Stronge (1985), Lal (1990) and Craddock (2005). The cast white metal of the objects is an alloy of zinc
the inlays are silver, brass or gold. The distinctive feature of bidri ware is its matt black patina which was the main focus of this research. None of the commonly occurring zinc compounds is black and no adequate explanation for the colour of the patina has yet been published. The patina is easy to produce in the laboratory on alloys of zinc with 2-10% copper, falling within the ε + η phase field of the binary copper-zinc equilibrium diagram, but it does not form on pure zinc or on brass (La Niece and Martin 1987). This study employed Field Emission Scanning Electron Microscopy with Energy Dispersive X-ray spectrometry (FE SEM-EDX) and X-ray diffraction (XRD) analysis to determine not only the chemical composition of the patinas, but also the morphology and distribution of the component particles. As a result it is now proposed that it is the ability of the patina particles, by reason of their small size and acicular form, to absorb light which gives the appearance of a matt black surface, rather than the existence of additional components within the patina.
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