Casting - Platinum
Platinum casting is carried out in a centrifugal machine as this is a high temperature material, and the vacuum pressure casting machines cannot handle this material. Special ceramic crucibles are required, as graphite will burn up at these temperatures. This is very much a manual casting operation. The platinum is melted again by induction coil, and when it has almost melted the hot mould is brought from the furnace and placed into its cradle next to the crucible.
As soon as the casting temperature is reached the operator lowers the induction coil and activates the spin cycle. With our machines this is manually controlled with regard to acceleration and speed so as to achieve the best possible result in terms of quality and surface finish. After casting the mould material is removed by quenching, high pressure water blasting, and finally by water and fine glass bead blasting, which removes 95% of the mould material. Finally the tree is pickled in hydrofluoric acid for total cleaning.
