Working with Bronze and Copper

This technique of metallurgy by sintering was used as early as the 19th century (perhaps earlier but I found nothing about it) to make titanium wires

Yellow bronze, gold color, is made of 90% copper and 10% tin, white bronze, silver color, is made of 80% copper and 20% tin

It all starts with metal dust...........

We add 10 parts of a cellulose binder (cornflour in the 19th century a) to 90 parts of this bronze or copper powder

Then a little distilled water is added and a clay-like malleable paste is obtained, which is worked in the same way than pottery clay .

It can be shaped, stamped, moulded... 

then I let them dry, the parts become very hard. They can then be sculpted, engraved, sanded, chiselled, polished,

Then a first firing is done at 300°C/572°F in an oxidizing atmosphere, i.e. in the presence of oxygen (air) in order to burn the binder that would prevent sintering. The parts then become anthracite grey and are very fragile

The pieces are placed in containers, and buried in charcoal. This creates an atmosphere called "reducing" so the bronze is fired away from oxygen, at 830°C / 1526°F for yellow bronze, 740°C / 1364°F for white bronze and 930°C / 1706°F for the copper

When the metal parts come out of the furnace, there has been sintering, the metal grains are welded together. The parts have shrunk by 10 to 20% and are oxidized, they must then be sanded, polished. Then I encaustic them with a wax that I make myself composed of orange peel essential oil and beeswax diluted with medical paraffin oil. All I have to do is mount them in bracelets, necklaces or earrings...

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