One of the finest 950 platinum casting alloys is platinum 950/cobalt 50, also known as 95/5 cobalt. This alloy has a very fine grain, high liquidity, and the ability to fill intricate detail. With a hardness of 135 HV and the ability to cast well and take a good polish, it is one of the most popular casting alloys in Europe and the United States
This alloy does oxidize, however. Because of this tendency, propane and other fuels do not work well with it. Instead, torch melting should be done with a hydrogen/ oxygen fuel mix, which does not permit much oxidation. This alloy is most successfully cast with induction heating in a controlled atmosphere.