I perform bronze casting using historical methods. Bronze casting is the casting of objects in the metal bronze. I melt the bronze by putting a crucible with metal in a charcoal furnace. Using hand-operated and handmade bellows the metal is heated to a temperature above 1000 degrees Centigrade! Then the bronze is cast in to a mould, made from soapstone or clay.
Prehistoric Bronze Casting
The emphasis in my bronze casting activities lies on using methods and techniques from the Bronze Age. This is the prehistoric period when the use of iron had not yet been discovered. In England this was roughly the period between 2150 and 700 BC. As fas as we know, during this period bronze casters mainly used furnaces where air was pumped in from above, using a clay pipe called a tuyère (as seen on the photo). This method is rather difficult, as the distance between the end of the tuyère and crucible below is crucial. A too small distance causes the cooler air to touch the metal, cooling it down. A too large distance results in the heat not reaching deep enough.
The metal bronze is an alloy (mixture) of copper and tin. Copper has a high melting point of 1083 degrees Centigrade. Tin already melts at 232 degrees. By adding tin to molten copper, we create bronze and lower the melting point in comparison to the copper. Bronze with the common proportion of 90% copper and 10% tin has a melting point of about 1000 degrees. Bronze is also much harder than copper and tin themselves.