The next procedure is to melt down the pieces of gold in a crucible with a borax flux, using a gas blowtorch. This is the stage at which extra gold is added if necessary. After melting the piece/s into a ‘billet’ of gold, it is then cooled before being soaked in safety pickling acid to remove all traces of oxidation, (the surface blackens when heated), to ensure once again there is no further contamination of the piece. Then after washing in water and drying, the process of shaping begins. This entails hammering and rolling the gold many times to create the desired new shape. Each time the gold is 'worked' it becomes hard and has to be heated with the torch to soften it (anneal it), in order to continue.