Bidri is a brass alloy, which
contains zinc, copper, lead, tin and traces of
iron. The usual yellow brass may contain not
more than 40-50 per cent zinc. Copper
constitutes the predominant phase.
After making the surface smooth, a solution
of copper sulphate is applied to the Bidri
Ware to darken it temporarity for engraving.
The engraving tools cut the intricate but
delicate tapestry of design into the metal,
which is then lighter in colour. Each piece is
then handed over to the inlayer. The inlay
may be of silver, brass or gold. The surface
of the decoration blackens after the inlay
has been burnished. This is done by
applying a paste of ammonium chloride,
potassium nitrate, sodium chloride, copper
sulphate and mud which darkens the body
by producing a characteristic black patina,
but without damaging the inlay.