Mokume Gane is a traditional metalworking technique and has been practised for some three hundred years. The technique requires a sandwich of different metals normally silver copper and copper alloys to be joined together either by diffusion bond or by silver soldering. This particular piece is made from six layers of silver, copper and gilding metal with a thick backing sheet of silver which have been hard silver soldered together. Once the billet has been soldered it is then forged and milled into a sheet and is ready to be patterned. The pattern can be produced in a variety of ways but all involve breaking through the top layer of metal into the ones below. The technique used in this piece is to punch down into the metal using a shaped punch. The raised areas between the impressions are then removed with a file - this breaks through the layers and produces the pattern. The sheet is then milled to produce a smooth patterned sheet of metal. The bowl is then spun, the silver rim added and the whole object cleaned and finally patinated using ammonia vapour.