This technique of metallurgy by sintering. has been used since the 19th century (perhaps earlier but I have not found anything about it) to make titanium wire.
The yellow bronze, bronze gold color, is made of 90% copper and 10% tin, the white bronze, silver color, is made of 80% copper and 20% tin.
It all starts with metal dust ……. to 90 parts of this bronze or copper powder we add 10 parts of a cellulose binder (in the 19th century maizena. I add distilled water and I obtain a malleable paste resembling pottery clay and which can be worked in the same way. I can then model it, stamp it, mold it…
Then I let it dry gently, 1 to 2 days to avoid cracking , the pieces become very hard. I can then sculpt them, engrave them, sand them, chisel them, pre-polish them,
Then a first firing takes place at 350°C in an oxidizing atmosphere, that is, in the presence of oxygen (from the air) in order to burn the binder that would prevent sintering. The parts then become anthracite gray and are very fragile
The metal pieces are placed in containers , buried in charcoal. This creates an atmosphere known as “reducing” and the metal is fired away from oxygen , at 830°C for yellow bronze, 740°C for white bronze and 930°C for copper
When the parts come out of the furnace, the metal grains have welded together. The parts have shrunk by 10 to 20% and are oxidized, they must then be sanded, polished . Then I encaustic with a wax that I make myself composed of essence of orange peel and beeswax diluted with medical kerosene oil .I just have to mount them in bracelets, necklaces, earrings …
